Dual Nutube 6P1
Rich triode overtones with excellent linearity and power efficiency.
IBASSOPORTABLE TUBE AMPLIFIERCustomer reviews (0)
iBasso PB5 Portable Balanced Tube Amp
Nutube warmth, balanced power.
A portable balanced amp with dual Nutube 6P1 tubes, a Super Class A discrete output stage and up to 1700mW per channel.
Regular price
£1,399.00
Unit price
Including VAT
Free next day UK delivery
Awaiting stock arrival date — order now to reserve one from the next delivery. Nothing to pay until it arrives.
THE AMP3 DIFFERENCE
Great gear. Even better service.
Order by 12 noon, Monday to Friday, for next day delivery. Destination and stock availability apply.
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iBasso PB5 Portable Balanced Tube Amp
A little extra. A better pairing.
Better together.
Hand-picked pairings for this product. Choose one — we'll add them together.
MEET THE PB5
Nutube warmth, balanced power.
A portable balanced amp with dual Nutube 6P1 tubes, a Super Class A discrete output stage and up to 1700mW per channel.
Six-battery supply
Separate batteries for the Nutubes and the output stage for pure power.
Stepped attenuator
A 24-position analogue volume with channel imbalance under ±0.1dB.
Read the full description
The iBasso PB5 Osprey is a portable balanced headphone amplifier with a pair of Korg Nutube 6P1 valves. A transistor current stage, six batteries and a 24-step stepped attenuator help it deliver 1,700mW per channel into 32Ω from a 4.4mm balanced line input.
Nutube voltage gain
The sixth-generation Nutube 6P1 from Korg and Noritake works like a conventional triode, with the same rich overtones, but uses far less power and space. It handles voltage amplification in the PB5. A two-step suspension reduces microphonics, and a cathode input lowers impedance to keep out interference.
Six batteries, real power
Two batteries power the Nutubes and four power the output stage. A TI OPA827 op-amp, low-saturation BISS transistors rated to 2A and iBasso’s custom film capacitors complete the circuit. Volume is a tiny 24-position, four-section stepped attenuator with channel matching within ±0.1dB, which lowers the noise floor along with the level.
| Input | 4.4mm balanced, up to 2.5V |
|---|---|
| Outputs | 4.4mm balanced (9Vrms) · 3.5mm single-ended (4.5Vrms) |
| Power | 1,700mW + 1,700mW @ 32Ω |
| Gain | +2dB (low) · +11.5dB (high) |
| Headphones | 8–600Ω recommended · output impedance 0.25Ω balanced |
| Battery | About 10.5 hours · 2.5 hours to charge |
| Size and weight | 139 × 82 × 28mm · 352g |
Good to know
- The input is 4.4mm balanced only, so your player needs a 4.4mm line output.
- Keep the input below 2.5V or it will distort. With iBasso’s DX220MAX, DX300MAX or DX320MAX, don’t use the highest line-out gain: it gives about 4.4–4.5V.
- This is an amplifier only: it has no DAC.
THE FINER DETAILS
Built for
better listening.
Know what you’re choosing.
Find the right fit for your setup.
- Headphone outputs
- 4.4mm balanced · 3.5mm single-ended
- Output power
- 1,700mW + 1,700mW @ 32Ω (9Vrms balanced · 4.5Vrms single-ended)
- Frequency response
- 20Hz–40kHz (+0.5dB/−2dB)
- Battery
- Six batteries · about 10.5 hours · 2.5 hours to charge
- Compatibility
- Headphones 8–600Ω
- Gain modes
- Low (+2dB) / high (+11.5dB)
- Output impedance
- 0.25Ω (4.4mm)
- Size (H × W × D)
- 139 × 82 × 28mm
- Weight
- 352g
- Amplification
- 2 × Nutube 6P1 input · Super Class A discrete output
- Inputs
- 4.4mm balanced (line level, under 2.5V)
- Power
- Battery (six cells)
Specifications are based on manufacturer information and may change. Battery life varies with use and settings.
The press, on the PB5
Independent ears.
Their verdict.
A different perspective on your next listen.
02 / Expert reviews
a beautifully smooth, weighty and fulsome sounding portable tube amplifier
Marcus
Read reviewHeadfonia
The PB5 improves the background, adds bass impact, enriches the midrange with a touch of organic character, and expands the soundstage
Recommended Buy
Yagiz
Read reviewSelected excerpts from published reviews. Scores are each publication’s own. Follow the links for their full verdicts.
FROM FELLOW LISTENERS
Customer reviews.
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How does free delivery work?
Every UK order has a free delivery option, and orders of £50 or more qualify for free next day delivery. Order by 12 noon, Monday to Friday, for next day delivery; orders placed after 12 noon, at the weekend or on a bank holiday are dispatched on the next working day. Stock availability and destination also affect arrival — check the options shown at checkout.
Pre-orders ship when stock arrives; the next day service starts after dispatch. Full delivery information
What if it’s not right for me?
Return within 14 days for any reason, or within 30 days if faulty, with free return postage. See our full Returns Policy for conditions and how to start a return.
Can you help me choose headphones?
Absolutely. Tell us what you listen to and the headphones you have — or the ones you’re considering — and we’ll help you find a suitable pairing. Chat with us
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Use the Price Beat option on this page to send us the competing offer. The team will review your request; it isn’t an automatic discount. How Price Beat works
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