I'm setting here listening to my HD800's and can't believe the other review about the HPA4 and HD800's 1cm sound stage and lack of bass... Doesn't match my experience on any level with the DAC3 DX driving the HPA 4 for the HD800's or the Utopia's.
All I'm hearing is stuff like it's supposed to be. Just extremely clean and detailed dynamics. Plenty of bass, just free of distortion so maybe that is where the difference in opinions comes from. I am used to extremely accurate and distortion free bass; I have 5 JL Audio subs (F113 x 3 and F212 x 2) on my main system that are time aligned using Room EQ Wizard, many bass traps, etc... Bass is absolutely dead on and portrays what is on the recording with the HPA4 (as well as my main system).
If someone likes using bass boost, nothing wrong with that. To say this unit can't supply enough power for accurate bass with the HD800's or that the soundstage is 1 cm with it is a bit puzzling. I'd love to see the other person's pics of their setup with the HPA4. I'm absolutely not saying there are shill accounts being used or anything of the sort. It'd be nice if people posted pictures of their headphones with the HPA4 so we could at least see what source component is being used though.