Cayin C9ii NuTube 6p1 Portable Headphone Amplifier

Cayin C9ii NuTube 6P1 Portable Headphone Amplifier

Take the reference listening room with you

Imagine the dynamics and microdetail of a great desktop stack—now battery‑quiet, tunable, and sized to travel. Cayin’s C9ii marries dual KORG NuTube triodes with a fully discrete, fully symmetric amplifier to deliver studio‑grade drive for full‑size cans and a jet‑black noise floor for the most sensitive IEMs. With three timbres (Classic Tube, Modern Tube, Solid‑State), Class A/AB/Hyper operation, adjustable anode voltage, and switchable feedback, it’s the rare portable that lets you fine‑tune synergy instead of settling for “good enough.”

---

Why audiophiles choose the C9ii

• • Sound quality: Triode sweetness when you want it, solid‑state precision when you don’t—backed by serious current delivery. Up to 4.1W balanced, with inaudible hiss on sensitive IEMs and authority for high‑impedance headphones.
• • Engineering: Fully discrete, fully symmetric three‑stage amplifier (JFET differential input, BJT voltage and current stages), Gen5 dual NuTube 6P1 tube circuit, precision dual MUSES electronic volume controlled by a 4‑gang ALPS knob.
• • Practicality: Tool‑free, quick‑release battery module with four user‑replaceable 18650 cells; USB‑C PD/QC fast charging; robust 6063‑T6 aluminum chassis with integrated heat‑sinks and graphite thermal pads.
• • Compatibility: 3.5 mm SE and 4.4 mm balanced inputs/outputs; switchable Line/Pre‑In; two gain levels; ultra‑low output impedance for stable pairings from ultra‑sensitive IEMs to planars.
• • Uniqueness: On‑the‑go “voicing” control—choose timbre (Classic/Modern Tube or Solid‑State), anode High/Low, NFB On/Off, and Class A/AB/Hyper to tailor tone, punch, staging, and texture to each headphone and track.

---

What’s included

• • C9ii main unit with pre‑installed battery module
• • CS‑35C35 II single‑ended interconnect (3.5 mm to 3.5 mm)
• • CS‑44C44 II balanced interconnect (4.4 mm to 4.4 mm with GND)
• • USB Type‑C charging cable
• • User manual
  Confirmed by the official user manual.

---

Technical Specifications

Specification	Value	Notes
Product type	Wired portable headphone amplifier	Analog; no DAC
Inputs	3.5 mm TRS line/pre; 4.4 mm TRRRS line/pre	Switchable Line/Pre‑In
Outputs	3.5 mm TRS; 4.4 mm TRRRS	SE and balanced headphone outs
Power (SE 3.5 mm)	1200 mW @16Ω; 700 mW @32Ω; 160 mW @150Ω; 80 mW @300Ω	High/Low gain modes
Power (BAL 4.4 mm)	4100 mW @16Ω; 2600 mW @32Ω; 640 mW @150Ω; 320 mW @300Ω	Drives full‑size dynamics/planars
Frequency response	SS: 11 Hz–80 kHz (±0.5 dB); Tube: 20 Hz–80 kHz (±0.5 dB)	Wideband extension
THD+N (SS)	0.002% (SE 16–32Ω); 0.001% (BAL 150–300Ω), 1 kHz, 1 Vrms, A‑wtd	Clean, low‑distortion baseline
Tube THD (Classic/Modern)	Typical 0.20–0.07% depending on mode/load	Intentional tube harmonics
Dynamic range (SS)	Up to 127 dB (Low Gain, BAL) A‑wtd	Black background
Output impedance	≤0.095Ω (Tube); ≤0.19Ω (SS)	Stable with low‑Z IEMs
Volume control	ALPS 4‑gang + dual MUSES72320 electronic volume	Precise, channel‑matched steps
Operating modes	Class A / Class AB / Hyper; NFB On/Off; Anode High/Low; Timbre: Classic Tube / Modern Tube / Solid‑State	On‑the‑fly tuning
Battery	4× Samsung INR18650‑35E (3400 mAh)	Replaceable module
Battery life	Up to ~17.5 h (SS, SE, Class AB); ~8–13 h in tube/balanced modes	Mode‑dependent
Charging	USB‑C PD2.0/QC3.0; ~3.8 h (fast) / ~6.5 h (standard)	Charge module in or out
Dimensions	165 × 88.5 × 30 mm	Transportable form factor
Weight	~650 g	Solid, vibration‑resistant build

Specs consolidated from the official manual and authorized retailer listings.

---

Professional recognition

• Awards: Headfonia Best of Year 2024 — Editor’s Choice. “A highly customizable and versatile portable amplifier… a showcase of advanced engineering.”
• Reviews:
  • Headfonia: “The C9ii is a powerhouse… with no hissing with sensitive multi‑BA IEMs.”
  • Headfonics: Notes tangible improvements in dynamic range and SNR versus the original, with emphasis on power quality and a blacker background.
  • SPILL (HK): Clear, practical guidance on how Classic/Modern tube modes, anode voltage, and NFB change body, sweetness, staging, and transient speed.
• Heritage: Built by Zhuhai Spark (Cayin), founded in 1993, with three decades of tube and solid‑state expertise in home and portable audio.
• Innovation highlights: Gen5 dual NuTube implementation; fully symmetric discrete 3‑stage topology; quick‑release 18650 battery module; optimized thermal design with CNC 6063‑T6 chassis and graphite pads.

---

The bottom line

C9ii is what happens when a tube expert rethinks portable amplification from the ground up—musical, muscular, and meticulously configurable. If you want the freedom to shape your sound without giving up silence, drive, or build, Cayin’s flagship portable amp earns its reputation—and a long‑term place in serious rigs.

---