Well, I received my A18 this afternoon and have been enjoying it ever since with both the Hifiman HE400 and Senn HD800s. The first thing that stands out to me is indeed the soundstage. Coming from a Violectric V200, which I felt had a little bit too intimate or congested of a presentation, the A18 certainly displays more depth and width. The aspect that I'm enjoying most, however, is actually the separation. Listening to orchestral works, the semi-circle made by the performers is readily evident, with distinct placement of your first violins, seconds, violas, and cello/bass section. The woodwinds in back are a little less distinct, though still good.
Like project86 said in his excellent review, the bass so far seems very comparable to the V200, and the highs are ever so slightly more rolled off. Also, this amp runs pretty hot! To the point where I don't really want to pick it up after it's been running for a couple hours. And if it's of any import, I am feeding the amp through the RCA inputs and listening through the 1/4" jack. Using the 300 ohm senns and the planar HE400s, there has been no hiss for me, up until about 4 or 5 o'clock for both headphones. For classical, I am listening between 10 and 1 o'clock, so this likely will not be an issue. I tried both outputs (tube and solid state) on my Minimax Plus DAC, and it seems to make no difference with regard to the high-volume hiss. As for sonic differences, I haven't quite figured any out in my limited listening.
So far, a very good purchase!
