Turn your desk into a reference listening station—wired precision, wireless freedom

Rediscover your library with the FiiO K7 BT, a truly balanced desktop DAC/amp that marries velvety AKM conversion with THX AAA muscle. It delivers the black backgrounds, effortless dynamics, and low-level detail audiophiles crave—plus the convenience of high‑resolution Bluetooth when you want to kick back cable‑free. Whether you’re driving planars at your desk or feeding powered speakers, the K7 BT is voiced for long‑session musicality without listening fatigue.

Why Audiophiles Choose This Product

• Bold, balanced sound with headroom to spare:
  Dual AK4493SEQ DACs feed dual THX AAA 788+ amplifier modules for clean, neutral drive with a hint of AKM “velvet” smoothness. Expect authority down low, a natural midrange, and grain‑free treble across a wide soundstage. Power is rated up to 2,000 mW into 32 Ω balanced and 560 mW into 300 Ω, so both low- and high‑impedance headphones sing.
• Engineering that measures and sounds right:
  A fully balanced, six‑stage audio circuit, XMOS XUF208 USB engine, and comprehensive protection (overheat/overload/DC) ensure low distortion and long‑term reliability. FiiO’s ADC curve reconstruction yields 112 precise, channel‑matched volume steps with silent background.
• Everyday usability, elevated:
  Front‑panel input and output mode switches, two hardware gain levels, a tactile volume wheel, and a status RGB ring make operation intuitive. Three output modes let you choose headphone out, variable pre‑out, or fixed line out at the touch of a button.
• Versatile connectivity for any desk:
  USB, optical, coaxial, and RCA line‑in cover digital and analog sources; 6.35 mm single‑ended and 4.4 mm balanced headphone outs plus rear RCA line‑out handle listening or speaker duty.
• Wireless done right:
  The BT edition adds a Qualcomm QCC5124 receiver (Bluetooth 5.1) supporting LDAC, aptX Adaptive, aptX HD, aptX LL, aptX, AAC, and SBC. Control codec selection, apply PEQ, and update firmware via the FiiO Control app for a tailored wireless experience. Note: App controls apply in Bluetooth mode only.

What’s Included

• Main unit: FiiO K7 BT balanced desktop DAC & headphone amplifier (dual AK4493SEQ DACs, dual THX AAA 788+ amps)
• Power adapter and AC cable: Low‑noise external 12 V / 24 W supply for stable performance
• USB cable: For computer connection (USB audio)
• Bluetooth antenna: For stable long‑range reception (K7 BT only)
• Documentation: Quick start guide and warranty card

Package items are per FiiO’s official listing; antenna inclusion for the BT model is confirmed in hands‑on coverage.

Technical Specifications

Professional Recognition

• Certifications: Displays Hi‑Res Audio and Hi‑Res Audio Wireless badges (Japan Audio Society), reflecting its ability to reproduce the full hi‑res spectrum via wired and LDAC wireless playback.
• Expert reviews:
  • “Easy to use, offers remarkable audio detail … and never introduced any ear fatigue during long playback sessions.” — TechHive.
  • “Fully balanced internal architecture … good Bluetooth performance.” — Headfonics on K7 BT.
• Heritage and engineering:
  • Shares the acclaimed THX AAA 788+ amplifier platform found in FiiO’s higher‑tier designs, democratizing reference‑grade drive at a compact desktop size.
• Thoughtful UX touches:
  • The RGB ring provides instant format/codec confirmation; input/output toggles and dual‑gain support fast, frustration‑free daily use.

The Bottom Line

The FiiO K7 BT hits a rare sweet spot: balanced desktop power, refined AKM tonality, and low‑distortion THX drive—plus modern, app‑tunable Bluetooth for when convenience calls. With serious I/O, three output modes, and enough clean headroom for today’s planars, it’s an easy recommendation for anyone building a high‑value, high‑fidelity desk setup that won’t box them into one way of listening. If you want one device that looks elegant, measures right, and simply lets your music flow, the K7 BT is built for the long haul.

• Dual RAYTHEON JAN6418 MIL-SPEC Vintage Vacuum Tubes
• Our TRIPLE AMP SYSTEM allows listeners to select the right tones for their music
• Three levels of voltage with Tube Current option
• Stainless steel with 99.9% pure silver plating
• Separate digital and analog signal processing (AK4191EQ x2 / AK4499EX x2)
• VU Meter
• High-performance Qualcomm Snapdragon CPU

Developing the extremely popular A&ultima SP3000 , Astell &Kern has
combined the best qualities of its current flagship player with the warm sound
of tube amplification. The SP3000T features Astell&Kern’s triple
amplification system, first introduced in 2021 on the A&ultima SP2000T, which
allows users to customize their audio profile using tube amplification, a
digital op-amp, or a hybrid combination of tube and op-amp.
All three modes are available when using the 2.5mm, 3.5mm or 4.4mm outputs.

What is it?

Analog Warmth, Digital Precision

Astell &Kern’s ethos of producing immersive sound from high-resolution
original music stands as a testament to the spirit of innovation and
excellence embodied in the A &ultima series. Our goal was to surpass the
impeccable design and high-resolution sound of our previous product, the
SP3000 , by crafting an audio player that truly captures the emotion and
resonance of music. Developed with this vision in mind, the A &ultima
SP3000T channels the profound emotion and lasting essence of analog audio.
The integration of a real vacuum tube creates an authentic analog sound
complemented by cutting-edge audio technology such as TERATON ALPHA for an
immersive auditory experience. Introducing the A&ultima SP3000T — a
portable audio player that defies convention, offering

• HEXA-Structure DAC Design
• Four AK4499EX and Two AK4191EQ DACs
• 32-Bit / 768 kHz and DSD512 (22.4 MHz)
• Qualcomm Snapdragon 6125 Octa-Core CPU
• 256GB Internal Memory
• Dual-Band Wi-Fi
• High-Definition 5.46" Touchscreen
• Balanced and Unbalanced/Optical Outputs
• Charging and Data Transfers via USB-C
• Includes Leather Case and USB-C Cable

Luxury Meets Innovation, SP3000

Astell &Kern has set the standard for perfect sound using the latest
innovative technology with the A &ultima series. The A &ultima SP3000
is the newest flagship product that is the essence of everything learned and
engineered over the last 10+ years of digital music processing.

A &ultima SP3000 is the world’s first DAP with independent Dual Audio
Circuitry and the latest DAC with HEXA-Audio Circuitry structure, as well as
uses all audio technologies and the best materials that lets you feel the
overwhelming impact of sound and music.

Experience perfection firsthand with the true next-generation flagship, A
&ultima SP3000, the pinnacle of audio players.

Materials Innovations: World’s First Use of Stainless Steel 904L for DAP

Body Material

To achieve the goal of the A &ultima series, which is ‘to provide the best
value that no one can imitate while using the most innovative and
uncompromising design and craftsmanship’, the SP3000 uses 904L stainless
steel material that has never been attempted before in a portable audio
player. Using this material has expanded its value from just a digital device
to the realm of a luxury good.

904L stainless steel is harder and more difficult to process than general
stainless steel requiring significantly more time and effort. However, due to
its excellent durability and corrosion resistance, it has a characteristic
that does not lose its beauty and is why it is used in expensive luxury
watches where perfection in all materials and parts must be pursued with an
irreplaceable and wonderful luster.

Experience the uncompromising beauty and luxury of the SP3000 produced by
Astell &Kern’s experienced craftsmanship.

TERATON ALPHA – The Essence of A&K Audio Technologies Merged Into the

SP3000

In order to develop the ultimate audio player that has never been experienced
before, not only do we use the latest DAC and technology available, but we use
the innovative audio technology of TERATON ALPHA, AK’s Ultimate Sound
Solution, which has been refined for the SP3000.

TERATON ALPHA, engineered through endless research, is Astell &Kern’s
unique technology that has been designed to produce audio playback that is
close to the original sound through effective power noise removal, efficient
power management and unwavering amplification, and a fully converted audio
output interface.

The HEXA-Audio Circuitry structure and independent dual audio circuit,
implemented for the first time in the SP3000 , are paired together with
TERATON ALPHA’s sound solution to create the purest original sound.

In the Box

• Astell & Kern A&ultima SP3000 High-Resolution Music Player (Silver)
• USB-C Cable
• microSD Card Slot Cover

• Dual RAYTHEON JAN6418 MIL-SPEC Vintage Vacuum Tubes
• Our TRIPLE AMP SYSTEM allows listeners to select the right tones for their music
• Three levels of voltage with Tube Current option
• Stainless steel with 99.9% pure silver plating
• Separate digital and analog signal processing (AK4191EQ x2 / AK4499EX x2)
• VU Meter
• High-performance Qualcomm Snapdragon CPU

Developing the extremely popular A&ultima SP3000 , Astell &Kern has
combined the best qualities of its current flagship player with the warm sound
of tube amplification. The SP3000T features Astell&Kern’s triple
amplification system, first introduced in 2021 on the A&ultima SP2000T, which
allows users to customize their audio profile using tube amplification, a
digital op-amp, or a hybrid combination of tube and op-amp.
All three modes are available when using the 2.5mm, 3.5mm or 4.4mm outputs.

What is it?

Analog Warmth, Digital Precision

Astell &Kern’s ethos of producing immersive sound from high-resolution
original music stands as a testament to the spirit of innovation and
excellence embodied in the A &ultima series. Our goal was to surpass the
impeccable design and high-resolution sound of our previous product, the
SP3000 , by crafting an audio player that truly captures the emotion and
resonance of music. Developed with this vision in mind, the A &ultima
SP3000T channels the profound emotion and lasting essence of analog audio.
The integration of a real vacuum tube creates an authentic analog sound
complemented by cutting-edge audio technology such as TERATON ALPHA for an
immersive auditory experience. Introducing the A&ultima SP3000T — a
portable audio player that defies convention, offering a unique fusion of
analog and digital excellence.

True Analog Sound with Real Vacuum Tube

The original vacuum tube is known for its warm sound, attributed to its
distinctive rich harmonics, which have cemented its status as a cherished
component of Hi-Fi audio. However, its impracticality in terms of
miniaturization, primarily due to power control and footprint issues,
presented a formidable obstacle, rendering it unsuitable for use in portable
audio players. In Astell &Kern’s unyielding quest for innovation, we
refused to settle for conventional sound and design, and instead worked to
bridge the gap between stationary and portable audio by infusing the essence
of analog sound into our devices. These efforts eventually culminated in the
pairing of the SP3000T with the RAYTHEON JAN6418 Miniature vacuum Tube.
The RAYTHEON JAN6418 is a mini vacuum tube popular among audiophiles. Designed
to meet military specifications and traditionally used in military
communication equipment, it quickly garnered recognition for its distinctively
warm and soft sound, leading to its integration into regular audio devices.

Sound Craftsmanship for the Ultimate Vacuum Tube Sound

Due to inherent differences in noise and amplification among original vacuum
tubes, Astell &Kern adopted a meticulous selection process to adhere to
our philosophy of addressing even the minutest differences in sound quality.
Astell &Kern carefully measures and pairs each JAN6418, a difficult
process demanding both time and precision. This thorough selection method
minimizes output deviation between the left and right channels, resulting in
more natural sound reproduction. Every shielding operation on the vacuum tube
is carefully executed by hand to minimize potential noise interference. Thanks
to our unwavering dedication to sound craftsmanship, we have successfully
brought the distinctive spatial sense and balance found in our existing audio
players into the analog realm of vacuum tube sound.

SP3000T Copper

Astell &Kern always strives to create more than just sound, focusing on
excellence in sound quality. TheSP3000T COPPER Edition demonstrates this
philosophy by delivering exceptional sound characteristics. Copper, known for
its excellent sound transmission and resonance properties, typically enhances
the brightness and richness of tones in musical instruments. This quality has
been repeatedly validated in Astell &Kern products using copper for its
outstanding electrical conductivity and high shielding performance. Copper,
because of its material properties, oxidizes and discolors upon contact with
air. The SP3000T COPPER Edition utilizes over 99.98% pure copper with a
special multilayer coating that enhances durability, ensuring it maintains its
beautiful color and luster without requiring special maintenance. Created
using proven Astell &Kern technology, the SP3000T COPPER Edition
offers more than just music—it provides an emotional experience beyond music.

We invite you to experience the emotions delivered by the pure original sound
of theSP3000T COPPER Edition.

What’s in the box?

• Astell & Kern A&ultima SP3000T High-Resolution Music Player
• Shrunken Calfskin Case
• Limited 1-Year Manufacturer Warranty

• Ultra-Precise 24-bit R-2R DAC
• TERATON ALPHA Technology
• Class A/AB Dual Amplifiers
• 2-Step Gain with up to 6 Vrms
• OS & NOS Modes
• Up to 12 Hours of Battery Life
• Native DSD256 32-bit/384 kHz
• 5.46" Full HD Display
• Crimson-Themed UI/UX
• Color-Coded Light-Up Volume Knob

Desciption

Fully Discrete 24bit R-2R DAC

To ensure the A &futura SE300 audio player better reproduces analog
sounds, we set out to combine the DAC and AMP sections for the first time
during the initial design phase.

The SE300 comes supplied with an R-2R DAC, instead of a Delta-Sigma DAC
that is most commonly used in other audio players. R-2R DAC, also known as
Ladder DAC, as it arranges resistors in a ladder form, offers natural yet
dynamic Hi-Fi sounds, but it is extremely technical and difficult to execute
as it requires complex refined resistor units and hard to manage current
controls. However, despite these technical challenges, after several years for
development and a lot of trial and error we have managed to overcome this and
create a new analog sound. In the process, we have meticulously selected each
and every one of the 96 ultra-precision resistors and finalized our R-2R DAC
technology.

SE300 takes us one step closer to realizing analog sound from a digital
source and is the result of a long journey taken by Astell &Kern with
uncompromising craftsmanship to find the ultimate sound solution.

Realization of 24-bit Decoding with R-2R DAC

The R-2R DAC within the SE300 arranges 48 pairs (23xR and 25x2R) of 96
ultra-precision resistors to create analog signals, in turn realizing true Hi-
Fi 24-bit decoding.

**Ultra-pre

• HEXA-Structure DAC Design
• Four AK4499EX and Two AK4191EQ DACs
• 32-Bit / 768 kHz and DSD512 (22.4 MHz)
• Qualcomm Snapdragon 6125 Octa-Core CPU
• 256GB Internal Memory
• Dual-Band Wi-Fi
• High-Definition 5.46" Touchscreen
• Balanced and Unbalanced/Optical Outputs
• Charging and Data Transfers via USB-C
• Includes Leather Case and USB-C Cable

Luxury Meets Innovation, SP3000

Astell &Kern has set the standard for perfect sound using the latest
innovative technology with the A &ultima series. The A &ultima SP3000
is the newest flagship product that is the essence of everything learned and
engineered over the last 10+ years of digital music processing.

A &ultima SP3000 is the world’s first DAP with independent Dual Audio
Circuitry and the latest DAC with HEXA-Audio Circuitry structure, as well as
uses all audio technologies and the best materials that lets you feel the
overwhelming impact of sound and music.

Experience perfection firsthand with the true next-generation flagship, A
&ultima SP3000, the pinnacle of audio players.

Materials Innovations: World’s First Use of Stainless Steel 904L for DAP

Body Material

To achieve the goal of the A &ultima series, which is ‘to provide the best
value that no one can imitate while using the most innovative and
uncompromising design and craftsmanship’, the SP3000 uses 904L stainless
steel material that has never been attempted before in a portable audio
player. Using this material has expanded its value from just a digital device
to the realm of a luxury good.

904L stainless s

Elevate your desk to concert level

Rediscover albums you thought you knew. The FiiO K7 brings balanced desktop power, vanishingly low distortion, and a subtly musical AKM presentation together in a compact, all‑aluminum body—so your favorite headphones finally sound as open, dynamic, and effortless as they should. Whether you’re driving power‑hungry planars or sensitive IEMs, K7 delivers clean headroom with the composure of a true hi‑fi component, not a dongle or laptop jack.

Why Audiophiles Choose This Product

• Genuinely engaging, high‑fidelity sound: Dual AKM AK4493SEQ DACs are known for a natural, slightly warm timbre that keeps detail intact without introducing glare—ideal for long sessions and mixed genres. Reviewers consistently describe the K7 as clean, dynamic, and fatigue‑free.
• Serious engineering where it counts: The fully balanced six‑stage signal path and dual THX AAA 788+ amplifier modules deliver ultra‑low distortion with abundant current, translating to grip and control on difficult loads. Independent LDO‑regulated power stages and multiple protection circuits keep performance stable.
• Desk‑friendly and intuitive: A solid aluminum chassis, tactile switches, and an ADC‑assisted volume system with 112 smooth steps prevent channel imbalance at low levels, so you can fine‑tune loudness precisely day or night.
• Versatile connectivity for any setup: USB‑B, optical, coaxial, and RCA line‑in cover computers, consoles, streamers, and DACs; 6.35 mm single‑ended and 4.4 mm balanced front‑panel outputs serve everything from IEMs to reference headphones. Three output modes let K7 act as headphone amp, preamp for powered speakers, or fixed DAC.
• Power with poise that outperforms its class: Up to 2000 mW per channel (32 Ω, balanced) or 560 mW (300 Ω, balanced) means confident drive for planars and high‑impedance dynamics; measurements from independent labs show excellent noise and distortion performance.

What’s Included

• FiiO K7 desktop DAC/amp: Dual AK4493SEQ DACs, dual THX AAA 788+ amps, truly balanced architecture.
• Primary accessories: 12 V / 2 A external power adapter and regional power cable; USB‑A to USB‑B data cable.
• Documentation: Quick start guide and warranty card.

Technical Specifications

Professional Recognition

• “Clean, engaging sound signature with no distortion… plenty of power to drive the vast majority of headphones.” — TechPowerUp.
• Independent measurements from L7Audiolab show excellent SINAD and multitone results from both single‑ended and balanced outputs, supporting its low‑distortion design.
• Head‑Fi community reviewers highlight its combination of power, low noise, and robust construction, calling it a “little beast” and praising its clear, natural sound.
• FiiO heritage: The K7 inherits architecture cues from the brand’s higher‑end K9 series—balanced topology, THX AAA amplification, and careful power management—distilled into a more compact, accessible chassis.

The Bottom Line

FiiO’s K7 is the rare “do‑it‑once” desktop upgrade: a truly balanced, low‑distortion DAC/headphone amp with the power, connections, and refinement to anchor your system for years. If you want a reliable, measurements‑backed step into serious desktop audio—without giving up musicality or desk space—the K7 sets a new baseline that’s hard to beat.

Notes and buying tips:

• This listing is for the wired K7 model. A separate K7 BT version adds Bluetooth codecs and app control if you need wireless input.
• For the best experience on Windows, install FiiO’s USB driver and use exclusive/ASIO mode in your player to auto‑match sample rates.

Big-stage sound, pocket-size freedom

Turn any phone or laptop into a serious hi‑fi source. Cayin RU3 brings clean, confident drive and a naturally musical tuning to your everyday listening—without the battery drain and bulk of a portable rig. If your pain points are flat dynamics, anemic bass, or hiss with sensitive IEMs, RU3 answers with 560 mW of balanced power, ultra‑low noise, and fine‑grain control over gain, filters, and EQ to match your exact gear and taste.

Why Audiophiles Choose This Product

• Strong, engaging sound: Neutral‑to‑slightly‑warm body with tight, punchy bass, clean mids, and relaxed, non‑fatiguing treble. Reviewers praised its “clean, powerful sound from a small package.”
• Engineered for fidelity: Built around ESS’s latest HyperStream IV ES9069Q DAC with dedicated I/V (TI OPA1602 ×2) and low‑noise headphone stages (SGM8262 ×2) in a true balanced architecture for excellent channel separation and low distortion.
• Practical everywhere: Hyper/Standard power modes optimize output and heat, while 100‑step hardware volume and two gain levels make it equally comfortable with sensitive IEMs and tougher over‑ears.
• Broad, reliable compatibility: USB‑C input with UAC 2.0 for up to 32‑bit/768 kHz PCM and native DSD512; switchable to UAC 1.0 for legacy devices and gaming consoles that prefer low‑latency class‑compliant mode. Works with modern Android, macOS, and Windows systems.
• App control that matters: The Cayin Control (Android) app adds a 10‑band parametric EQ, balance, filter selection, power/gain modes, and 100‑step volume—settings are stored in the RU3 itself for use across sources.

What’s Included

• RU3 Portable USB DAC/Headphone Amplifier: ES9069Q DAC, 3.5 mm SE and 4.4 mm balanced outputs (PO/LO shared) with color IPS display.
• USB‑C to USB‑C interconnect cable (short) for phones/tablets/laptops.
• User manual and documentation.

Note: Lightning/USB‑C adapters for older iOS devices are not included.

Technical Specifications

All figures per the RU3 official manual and Cayin product listing.

Professional Recognition

• Reviews: Headfonics concludes, “The Cayin RU3… delivers competitive output power… with clean, high‑quality sound,” and highlights its app integration and drive authority at this size.
• Heritage: Cayin is the hi‑fi brand of Zhuhai Spark Electronic Equipment Co., Ltd., designing acclaimed tube amplifiers and personal audio since 1993—bringing that musical house sound to compact devices like RU3.
• Thoughtful innovation: UAC 1.0/2.0 switching for broader device support, PO/LO mode from both 3.5 mm and 4.4 mm, and Android app‑based parametric EQ are rare at this size and class.

The Bottom Line

Cayin RU3 is the dongle to reach for when you want genuine hi‑fi dynamics and refinement from a phone or laptop, not just “good for a dongle” sound. The combination of ESS’s latest DAC, balanced architecture, robust power on the 4.4 mm output, and smart app control makes RU3 a confident daily driver for both sensitive IEMs and many full‑size headphones. If you’ve been underwhelmed by thin, bright, or underpowered dongles, RU3’s warm‑leaning neutrality, control, and headroom deliver the musical ease and authority you’ve been missing.

Notes for setup and compatibility:

• For Windows 10/11, plug‑and‑play works; Cayin’s optional USB audio driver enables ASIO for advanced apps. macOS and modern Android are driverless. Use UAC 1.0 if a legacy device or console requires it.
• Line‑out (LO) is selectable from either jack and shares the same amplifier path—ideal for feeding powered speakers or external amps on the go.

Turn any source into rich, high‑resolution listening—wirelessly or wired

Stop choosing between convenience and fidelity. Cayin’s BTC‑2 brings true hi‑res Bluetooth to your desk and adds a clean, punchy headphone amp and full DAC hub in one compact, all‑metal chassis. Stream in via LDAC or aptX HD, plug in a coaxial digital source, or feed it analog line‑in—then enjoy balanced 4.4 mm or 6.35 mm headphone output, send line‑level to powered speakers, or even pass digital out to a separate DAC. It’s the small box that brings every source together, without sacrificing sound.

Why Audiophiles Choose This Product

• Primary Benefit: Clean, detailed sound with a natural, non‑fatiguing presentation and a wide, well‑organized stage—impressive for a Bluetooth‑enabled desktop unit. Independent reviewers praise its finesse with strings and vocals and its composure on complex passages.
• Technical Benefit: Proven ESS Sabre ES9018K2M DAC paired with Qualcomm’s QCC5125 Bluetooth SoC and a balanced 4‑channel amplification path, for low noise and precise channel control.
• Practical Benefit: Simple front‑panel controls with a silky ALPS volume potentiometer and a crisp 1.7" white OLED display that shows input, codec, and sample rate at a glance. The detachable SMA antenna optimizes wireless reception.
• Compatibility Benefit: Bluetooth 5.1 (LDAC, aptX HD, aptX LL, aptX, AAC, SBC), S/PDIF coaxial input up to 192 kHz/24‑bit, and stereo RCA line in/out let BTC‑2 integrate with phones, tablets, PCs, TVs/set‑top boxes with coaxial out, and powered speakers.
• Unique Benefit: Acts as a Bluetooth receiver and digital hub—decode to its own headphone/line outputs or forward a Bluetooth stream as coaxial S/PDIF to an external DAC. Few compact units offer both S/PDIF in and out at this price class.

What’s Included

• Main Product: Cayin BTC‑2 Hi‑Res Bluetooth DAC/Headphone Amp (balanced 4.4 mm and single‑ended 6.35 mm headphone outputs; RCA line in/out; RCA coaxial S/PDIF in/out).
• Primary Accessory: USB‑C power cable (5V/1A input). Power adapter not always included; any 5V/1A USB power source works.
• Secondary Items: Detachable “rubber‑duck” SMA antenna for Bluetooth reception; infrared/Bluetooth remote is available and bundled in some regions, but is an optional accessory per Cayin.
• Documentation: User manual and warranty information (regional terms vary).

Technical Specifications

Notes:

• BTC‑2 is a Bluetooth receiver/DAC/amp. It does not transmit Bluetooth audio from wired inputs.
• Some retailers note user‑selectable digital filters (Fast/Slow/Minimum‑phase) accessible via the menu; availability can be region/firmware dependent.

Professional Recognition

• Reviews: Regional reviewers highlight BTC‑2’s “small size, big performance,” calling out airy staging, strong vocal detail, and confident layering—even over Bluetooth.
• Retailer Feedback: Specialty dealers emphasize its rare mix of LDAC reception plus both coaxial S/PDIF input and output, making it a flexible desktop hub.
• Heritage: Built by Cayin (Zhuhai Spark Electronic Equipment Co., Ltd.), a hi‑fi manufacturer established in 1993 with deep expertise from tube amplifiers to modern desktop and portable audio.
• Engineering Touches: ALPS volume potentiometer and robust metal enclosure for EMI shielding and long‑term reliability.

The Bottom Line

If you want simple, stable hi‑res Bluetooth for your desk without giving up the fidelity of a wired DAC/amp, Cayin’s BTC‑2 nails the brief. It consolidates your wireless streaming, digital coax, and analog sources into one elegant box—with balanced headphone drive and the option to feed an external DAC when you’re ready to upgrade further. It’s a thoughtfully engineered, future‑friendly desktop hub from a brand with three decades of audiophile credibility.

Big-stage sound, pocket-size freedom

Turn any phone or laptop into a serious hi‑fi source. Cayin RU3 brings clean, confident drive and a naturally musical tuning to your everyday listening—without the battery drain and bulk of a portable rig. If your pain points are flat dynamics, anemic bass, or hiss with sensitive IEMs, RU3 answers with 560 mW of balanced power, ultra‑low noise, and fine‑grain control over gain, filters, and EQ to match your exact gear and taste.

Why Audiophiles Choose This Product

• Strong, engaging sound: Neutral‑to‑slightly‑warm body with tight, punchy bass, clean mids, and relaxed, non‑fatiguing treble. Reviewers praised its “clean, powerful sound from a small package.”
• Engineered for fidelity: Built around ESS’s latest HyperStream IV ES9069Q DAC with dedicated I/V (TI OPA1602 ×2) and low‑noise headphone stages (SGM8262 ×2) in a true balanced architecture for excellent channel separation and low distortion.
• Practical everywhere: Hyper/Standard power modes optimize output and heat, while 100‑step hardware volume and two gain levels make it equally comfortable with sensitive IEMs and tougher over‑ears.
• Broad, reliable compatibility: USB‑C input with UAC 2.0 for up to 32‑bit/768 kHz PCM and native DSD512; switchable to UAC 1.0 for legacy devices and gaming consoles that prefer low‑latency class‑compliant mode. Works with modern Android, macOS, and Windows systems.
• App control that matters: The Cayin Control (Android) app adds a 10‑band parametric EQ, balance, filter selection, power/gain modes, and 100‑step volume—settings are stored in the RU3 itself for use across sources.

What’s Included

• RU3 Portable USB DAC/Headphone Amplifier: ES9069Q DAC, 3.5 mm SE and 4.4 mm balanced outputs (PO/LO shared) with color IPS display.
• USB‑C to USB‑C interconnect cable (short) for phones/tablets/laptops.
• User manual and documentation.

Note: Lightning/USB‑C adapters for older iOS devices are not included.

Technical Specifications

All figures per the RU3 official manual and Cayin product listing.

Professional Recognition

• Reviews: Headfonics concludes, “The Cayin RU3… delivers competitive output power… with clean, high‑quality sound,” and highlights its app integration and drive authority at this size.
• Heritage: Cayin is the hi‑fi brand of Zhuhai Spark Electronic Equipment Co., Ltd., designing acclaimed tube amplifiers and personal audio since 1993—bringing that musical house sound to compact devices like RU3.
• Thoughtful innovation: UAC 1.0/2.0 switching for broader device support, PO/LO mode from both 3.5 mm and 4.4 mm, and Android app‑based parametric EQ are rare at this size and class.

The Bottom Line

Cayin RU3 is the dongle to reach for when you want genuine hi‑fi dynamics and refinement from a phone or laptop, not just “good for a dongle” sound. The combination of ESS’s latest DAC, balanced architecture, robust power on the 4.4 mm output, and smart app control makes RU3 a confident daily driver for both sensitive IEMs and many full‑size headphones. If you’ve been underwhelmed by thin, bright, or underpowered dongles, RU3’s warm‑leaning neutrality, control, and headroom deliver the musical ease and authority you’ve been missing.

Notes for setup and compatibility:

• For Windows 10/11, plug‑and‑play works; Cayin’s optional USB audio driver enables ASIO for advanced apps. macOS and modern Android are driverless. Use UAC 1.0 if a legacy device or console requires it.
• Line‑out (LO) is selectable from either jack and shares the same amplifier path—ideal for feeding powered speakers or external amps on the go.