I would beg to differ, with respect to A5 sounding too dark and compressed. In fact, I find that when used with my various sources it tends to widen the soundstage and invaraibly sounds more transparent than the built in amplifiers in my gears. When paired with my best sources it sounds immense.
The A5 is not "bright", but that should not be conflated with being dark in my opinion. It is neutral and transparent, with perhaps a smidge of airyness up top. Too many gears add a certain flavor, for example treble forwardness and make claims of being more detailed. Frankly, FiiO tuned the A5 right. It adds NO flavor of its own, but rather let the DAC speak for itself.
Also, you will notice that most manufacturers (teh ones that know better) do not directly enter debates about sound qualities unless it pertains to a defect or an issue that they can help with. Cheers.