iBasso AMP19 Nutube + Super Class A Amplifier Card for DX340

Nutube + Super Class A Amplification

The iBasso AMP19 is an interchangeable amplifier card designed for the DX340, combining two distinctly different amplifier technologies within a single compact module.

Listeners can choose between the rich, relaxed character of Nutube vacuum tube amplification or the powerful, high-density presentation of iBasso's fully discrete Super Class A amplifier, allowing the DX340 to deliver two different sound signatures from a single amplifier card.

Nutube 6P1 Vacuum Tube

AMP19 uses the sixth-generation Nutube 6P1 triode vacuum tube, jointly developed by Korg and Noritake.

Designed to bring the sonic characteristics of traditional vacuum tubes to a portable audio player, the Nutube 6P1 delivers a warm and natural presentation with engaging vocals, softer textures and an analogue-inspired character.

Compared with conventional vacuum tubes, Nutube is significantly smaller and more energy efficient while retaining the distinctive qualities associated with tube amplification. The Nutube 6P1 offers a lifespan of more than 30,000 hours, uses approximately 2% of the power of traditional tubes and is around 30% of their size.

Two Output Modes

AMP19 provides two dedicated output modes, giving DX340 users a choice between two amplifier designs.

Tube Mode uses the Nutube 6P1 as the preamplifier tube, adding harmonic richness and producing a warmer, more relaxed and natural presentation. Vocals and instruments have a softer texture, creating a distinctly analogue character.

Super Class A Mode uses 20 dual transistors to form a fully discrete amplifier capable of delivering up to 2A of current. The substantial current reserve provides powerful energy and dynamics, fast transient response, a fuller presentation and excellent vocal density and texture.

12V DC External Power

AMP19 supports iBasso's 12V DC-IN external power technology.

When connected to an external 12V DC power source, the headphone amplifier power supply increases from ±6.5V to ±12V, allowing AMP19 to deliver up to 2150mW + 2150mW into 32Ω.

This gives the portable DX340 considerably greater driving power when paired with more demanding headphones.

JRC Hardware Volume Control

In Tube Mode, AMP19 uses a JRC hardware volume control with 100 fine adjustment steps.

Volume is adjusted through an analogue method rather than digital attenuation, allowing the DAC signal to remain intact while preserving audio fidelity.

The system also helps reduce output noise at low listening levels while maintaining detail and musical layering, making precise adjustment possible with both high-sensitivity in-ear monitors and high-impedance headphones.

APx555 Precision Testing

Each AMP19 is tested using an Audio Precision APx555 audio analyser before shipment.

iBasso engineers manually calibrate and match the Nutube circuitry using four hardware multi-turn potentiometers, helping ensure consistent Nutube 6P1 operation and sound between individual amplifier cards.

PORON Suspension System

To minimise the microphonic effects that can occur with vacuum tube designs, iBasso uses a suspended mounting system for the Nutube 6P1.

PORON material suspends the tube within the chassis, helping absorb shocks and vibration while reducing unwanted microphonic effects during portable use.

Designed for the DX340

AMP19 is specifically designed for use with the iBasso DX340.

The DX340 requires firmware V1.08 or above to use the AMP19 amplifier card.

Specifications

Super Class A Mode

4.4mm Balanced Phone Out

Output Level:
8.3Vrms – Super Gain
5.8Vrms – High Gain
3.8Vrms – Mid Gain
1.8Vrms – Low Gain

Output Power:
2150mW + 2150mW @ 32Ω – 12V DC-IN
1000mW + 1000mW @ 32Ω – Battery

THD+N: -109dB (A-weighted, 300Ω load)
Signal-to-Noise Ratio: 121dB
Dynamic Range: 121dB
Crosstalk: -114dB
Frequency Response: 10Hz–40kHz ±1dB
Output Impedance: 1.4Ω

3.5mm Single-Ended Phone Out

Output Level:
4.15Vrms – Super Gain
2.92Vrms – High Gain
1.89Vrms – Mid Gain
0.89Vrms – Low Gain

Output Power:
500mW + 500mW @ 32Ω – 12V DC-IN
260mW + 260mW @ 32Ω – Battery

THD+N: -105dB (A-weighted, 300Ω load)
Signal-to-Noise Ratio: 110dB
Dynamic Range: 110dB
Crosstalk: -114dB
Frequency Response: 10Hz–40kHz ±1dB
Output Impedance: 0.7Ω

Tube Mode

4.4mm Balanced Phone Out

Output Level:
7.7Vrms – Super Gain
4.53Vrms – High Gain
2.92Vrms – Mid Gain
1.55Vrms – Low Gain

Output Power:
1850mW + 1850mW @ 32Ω – 12V DC-IN
590mW + 590mW @ 32Ω – Battery

Frequency Response: 10Hz–40kHz ±1dB
Output Impedance: 1.4Ω

3.5mm Single-Ended Phone Out

Output Level:
3.7Vrms – Super Gain
2.3Vrms – High Gain
1.49Vrms – Mid Gain
0.79Vrms – Low Gain

Output Power:
428mW + 428mW @ 32Ω – 12V DC-IN
165mW + 165mW @ 32Ω – Battery

Frequency Response: 10Hz–40kHz ±1dB
Output Impedance: 0.7Ω