Adcom pre amp versus Van Alstine

Why just these two brands?  Many more options out there.  Also, the Adcom has well-documented reliability issues so I’d definitely avoid that as there are many, many other great options out there.  You should really start with what sound characteristics you’re looking for because AVA and Adcom can sound quite different.

Of the two, I’d pick the Van Alstine, in case I was too long winded. I might check out this one from a list of possibles:

There's also an ARC SP-6 out there for an under $1k price, and an Aric.

i've never heard the VA, so can't opine on it. however, i have owned the adcom 750  and it was  excellent--it's a nelson pass design which is on a completely different level than adcom's cheaper gtp (preamp w/tuner) models. it had a passive mode which was really transparent and sounded even better than the active mode. that said, other posters make a valid point about the reliability of older gear--i think the models you're looking at are 25+ yrs old--but the 750 is a serious piece.

At the prices these units command, buy both and evaluate on your own time. Report back here with the winner. Everyone loves a shootout. 

I have decided to buy them both! I will circle back with my review of both.