I know that I'll get a barrage of smirks and snickers from a lot of folks, here, who are into the rarified air of pricey(overpriced?) boutique amps, but I listened very critically for some time to a friend's AKG 701 and Grado 225 'phones through his Presonus HP4 amp/Presonus EQ3B 3-band equalizer setup, and was very favorably impressed. The equalizer allows for fine tuning the sound.
At a paltry $200 for the pair of Presonuses, it's got to be a great value when considering the amazingly good sound that one gets through these.
I do think, however, that the definitive reviews of such low priced amps would be obtained if several critical listeners compared them with higher priced amps, doing a blind comparison; reviewers would not know which amps are being reviewed nor even see them, but could only judge them entirely and only by listening.
I really think that many who look down their noses at inexpensive, "non-audiophile" amps like the Presonus HP4 already have a mindset that just won't allow them to admit that the sound from them is as good as it really is.
The audiophile mindset does tend to lend itself to a fair amount of arrogance, pretentiousness and elitism, where the bling factor often seems to be so seductive.