As a 9 year A250 user, I have tried more than one preamp. I haven't tried them all, but enough that some generalizations come forward. Generally, the A250 can be bright through the mids and highs (maybe a bit grainy) with a stong midbass and bottom, although it doesn't go too deep. Given these charachteristics, the preamps which share these traits tend to be a poor match--mostly ss. Instead I look for something more complimentary: mostly tubes. On the solid state side, I have tried Brystons (.4 & .5--same, but one has phono--I think), and a B&K; never tried the Acurus. They all tended to share the sonic traits of the A250--in the case of the Bryston it was kinda bright (an understatement--yikes!).
So, to smooth things out, I plugged in a Counterpoint. The oldest (?) model, SA-3. Ahhhh. Much better. Liquid mids, tame and listenable highs. Good midbass, slightly less good bass. Not wooly bass, but not as controlled as I've heard. Bottom line: the Counterpoint can be had at $300 used and really makes for a nice combo. My only complaint is that with sensitive speakers, the A250 has so much gain that the volume control on the Counterpoint is kept low except when I'm really rockin' out. Now, a low volume control setting is no big deal on the surface. But, as was explained to me by Mike Elliott, who was manufacturer of Counterpoint originally and now services them through http://www.altavistaaudio.com/, the volume control is least linear at lower settings. Basically, the volume out of one speaker is different from the other at lower levels. This balances out as the volume increases, but requires judicious use of the balance control during late night low-level listening. With less sensitive speakers, I didn't notice this as much.
Anywho, I think you'd dig the Counterpoint/A250 combo. That is, I do. It's musical, and accents the A250 strengths while minimizing it's deficiencies. With hyper-expensive gear a purist would scoff at the idea of this "sonic girdle" to control the sound, but for less than a kilobuck, this combo makes good sound.
