I picked up a WA8 a couple weeks ago to use at the office. My initial impressions are very positive. I'm mainly listening through my UE 18+ CSX iem's. With the stock tubes (the delivered driver tube in mine is a Thomson) I find the imaging is very good, detail retrieval strong, and overall quite pleasant. I do find that vocals in the middle of the soundstage have a slight veil, vs ones that are to the side. I also got the Sylvania 6BF7 upgrade driver tube and enjoy this configuration a bit better, with vocals really blooming, the bass being a bit deeper, and that center veil disappearing. Overall I find the soundstage to be quite wide but not very deep which can sometimes lead to some congestion in the middle of the soundstage with complex multi-instrument music. It is really well suited to acoustic, bluegrass, and jazz.
I also tried the WA8 with my Audeze LCD2's. I usually use these in my main rig (Benchmark 2 Dac -> Leben CS300 -> LCD2) where the LCD2 + Leben combo is magic, especially with the right tubes. With the WA8 I definitely enjoyed the LCD2's, although the soundstage isn't as big as with the Leben and overall the control and impact, especially in the bass, isn't at the same level. The WA8 has no problem driving the LCD2's, with a comfortable volume around 5.
Overall I think the WA8 is a great option for people who need some portability and a smaller footprint. The Sylvania driver is definitely worth it if you vocals are at the top of your list.