Outputting a -6 dBFS dithered 1 kHz sine wave (16bit 48 kHz) from the controller using REWs own signal generator.
RME Babyface Pro FS (set to 48 kHz internal clock) unbalanced inputs 3/4 used set to -10 dBv and +5dB gain for ~ -6dBFS input.
Doesn't look good at all.
As for the EQ changer button, I just sent pink noise out of Reaper to the controller and back into RME BFPro Fs.
Captured and overlayed. Green is pink noise, blue is with the EQ button. Hmmm 'clarity'.
Though I should note that this button was only intended to help accentuate certain things in games, not to improve musical qualities.
No idea what chip is being used in this controller for audio duties. Basic 16/48 DAC/HP-amp chips are almost free of charge, would not surprise me to find it being yet another dirt cheap part. This controller has to contain 4 analog inputs (2 sticks, 2 triggers) plus over 10 buttons, a D-pad and a pair of female personal entertainment devices!