My initials (vs dx90)
HP: NAD Viso HP50
Tracks: Mainly avant-garde metal (Diablo Swing Orchestra) and psychadelic rock (Camel)
Having had dx90 since its release you can guess how was I deeply accustomed to its sound q. Now using hp50, which a too revealing, and dx90's hiss at gain 2 and 3 became obvious.
Now comes the rough differences:
1. Obviously: SIZE. While dx90 has some old fashioned looks QA is not that large if encountered alone in the nature
2. Connectivity: Dx90 had many options. HP, Line, Coax were its -outs. QA has hp, analog, optical (3.5mm), IR out, 5v power out.
3. Sound: dx90 was almost bright and clear. QA is neutral to its bones. And clearer.
Bonus: Tried dubstep: Fuller and more "realistic" as computer generated sound could be. And fiercier especially in the bass drop phases. Plus basses hit harder at chords.
Bonus2: Röyksopp - Only This Moment: Backing vocal is obvious. Music got elevated into something else with QA
Bonus3: Pain of Salvation - Remedy Lane (FLAC - almost crystal clear now)
Bonus4: Gorillaz - Feel Good INC (Flac): Wow. Was wondering how more this device could get better?! Now listening almost a brand new song than the same song I am listening for nearly a decade.
These recordings are done out of the QA. Will try using a hybrid Schiit Vali clone tomorrow. And a dedicated tube amp Monday.
ps: Couldnt get to vol 250 at dx90. Can never listen at 150 with this one. 70 does it.
ps2: QA is buttoned like ancient devices. No iphone class touch screen.