15dB attenuation in signal sent to USB DAC

[hb1ac]

USB Audio Player Pro is attenuating 15dB the signal it sends to the USB DAC despite having the volume control at 0dB. 

If I play a sound file (1khz 0dBFS) on a FiiO K3 I get an output signal of 0.355 Vrms in line out.
If I play it from Android with VLC I get an output signal of 1.999 Vrms in line out. This is correct since FiiO k3 has in the specifications a maximum output of 1.9 Vrms.

I have done the test in a Redmi A6 phone and in a FiiO X5 III with the same result: 0.355 Vrms instead of 1.9 Vrms what is right.

Sorry for my English. It is not my native language.

[dwrae]

If the app displays 'USB DAC' in front of the target sample rate, please press the volume/EQ button at the top, then press the button called 'Hardware volume' and see if there are multiple sliders. If so, please raise them. If you don't see 'USB DAC' but Android or Direct, then you are not using our driver. In that case, please try restarting your Android device with the DAC attached.

[hb1ac]

Thanks for the reply.

With maximum software volume it does not work BUT with hardware volume it does.

SOLVED!!!