Haha! That up there is an educational example of how not to base opinions on hearing only 2 songs. After a day with it, I can't say that at all any more. Gor my tastes and my equipment, which is the u18, amp8 is not nearly as right as amp 4 (I'm talking original 4, not 4s). The 8 is an improved 4s, without the bad soundstage and lack of detail, but the 4 original is still way clearer to my ear. It also has a remarkably wider soundstage and a mid centric emotional sound that favours vocals and instruments. What the 8 brings is bass, just TONS of it, fatiguingly so for me. And soundstage depth and separation along the z axis, which is nice, but not a tremendous improvement over the 4 either, whic is already very holographic. It's also just louder, seems to have more power.
I'm clearly not an authority at this point, having flippy-floppied around like that, but really, the original 4 is the most reference and hifi sounding amp for the dx200, clearly. While the 8 is a fun musical amp with plenty of detail and nice depth, a much better 4s, but not quite that end game pristine upper midrange and treble that that 4 has. Also the 4 is very non fatiguing, while the 8s bass is quite hard on the ears with the u18. Burn in could have something to do with it all, but I doubt I'll get 50 hours in with this, given how much better going back to amp 4 sounded to me.
