NX4    Portable Headphone Amplifier with built-in USB DAC
Built-in USB DAC

Built-in USB DAC of NX4 could use for iphone, ipad's lightning port, an Android phone's USB or a PC's USB.

*note for Android phone: Only compatible with the Android phone which support OTG and external USB sound card.


NX4 use OP+BUF structure. OPA1642 for input and 2 x LMH6643 for buffer. THD+N is as low as 0.0003% ( 1kHz, 300ohm, 17nW, Gain=L)

Full Aluminum Shell

We use a highly automated machining center to make NX4’s aluminum shell.

High-power laser engraving

All characters was made by high power laser, it will never fall off.

Gain switch and Bass boost

NX4 has a gain switch to meet different needs.

NX4 also has a bass boost circuit, it boosts only mega bass effect to you while bass on. Mega bass circuit will be fully cut off and it will not bring you extra distortion and noise while it was switched off.

Lo batt LED

The power LED turn red to remind you NX4 is in lo batt condition, you need to charge it immediately to avoid damage to the battery.

Charging progess display

Red means NX4 is in charging and green means NX4 had finish charging.

No POP noise

We use NEC relay to void POP noise of turning on and turning off the NX4. This protects your hearing and your headphones.

Less ripple, less background noise

NX4 use tantalum capacitor and higher frequency DC-DC power supply to lower the ripple. This make NX4's background noise lower.

36 Hour playback time

2400mAh Lithium Ion battery provide 36 hour playback time for NX4's headphone amp or 12 hour playback time for USB DAC + headphone amp.

The battery needs less than 4 hour for a fully charge.

Adaptive Charging

NX4 automatic fits 0.5A current from PC’s USB port and 1A current from a USB charger. It takes less than 4 hour to fully charge NX4 at 1A charge current.


NX4 has CE, ROHS and FCC certification.

Compatible with all USB interfaces

No matter what your USB interface is, NX4 works well with it. This including Micro USB of Android phone, type-C of Android phone, Lightning of iphone or ipad, even your PC.

*note for Android phone: Only compatible with the Android phone which support OTG and external USB sound card.

Analog input 1 x 3.5mm(share with analog output)
Analog output 1 x 3.5mm(share with analog input)
Headphone output 1 x 3.5mm
Playback time

Approx 30 hours (only headphone amp)
Approx 12 hours (USB DAC + headphone amp)

Net weight Approx 155g (unit only)
Dimensions Approx 11CM x 6.8CM x 1.4CM
Includes 1 x NX4
1 x audio cable
1 x USB charge cable
1 x Micro to Micro cable
1 x Micro to Type-C cable
1 x Micro to Lightning cable
2 x Rubber band
1 x Rubber pad
5 x Velcro
1 x User's manual
1 x Warranty card
Suitable Headphone Impedance 16-300Ω
Maximum output power 307mW x 2 (Gain=L, RL=32Ω, THD+N=1%)
35mW x 2 (Gain=L RL=300Ω, THD+N=1%)
Maximum output voltage swing 9.2Vpp
THD+N(@1kHz) 0.0010% (RL=32Ω, Gain=L Pout=5mW)
0.0003% (RL=300Ω, Gain=L Pout=5mW)
Frequency response 10-200kHz
Input sensitivity 3.3Vrms (Gain=L); 1.2Vrms (Gain=H)
Noise <2.9μV (RL=32Ω, Gain=L)
<8.0μV (RL=32Ω, Gain=H)
Gain(@1kHz) +0dB (Gain=L); +9dB (Gain=H)
SNR 120dB(Gain=L)
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