I had a Benchmark AHB2 for almost 3 years and really enjoyed the clean sound and wide stage. I decided to make a big jump about 2 years ago to the Pass 250.8 and instantly heard why people enjoy Pass. The soundstage was deeper, taller, and most importantly it made listening more fun. Instruments and vocals had more weight/tone to them and the soundstage felt more cohesive than the AHB2.
This is exactly how I felt when I dropped an AHB2 into my system which was anchored by an X250.8. I really liked the AHB2 for the $$ and how clear it was, but I found it lacked the front to back soundstage depth and life-like texture and tone of the Pass. I sold it after a month or two and kept the Pass for like 5 years.
@robshaw, if the 250.8's hint of warmth, musicality, lack of any harshness, and a killer soundstage interests you, I recommend you listen to the AtmaSphere Class D monos. They come very close (IMO) to the 250.8 and XA30.8 sound signatures that I'm very used to. I now own a pair of the AtmaSphere monos and am very happy with them.