Usually these days I buy oline after reading some reviews and talk/chat to people that have first-hand experience. At Thomann, I can return products within 30 days without costs, so that's pretty safe.
I'd like to add the ART PRO CHANNEL II to the list. It becomes a new hype among bass-player as a pre-amp. There is a lot of love for this unit around here and it is 300€ new (afaik
the US price is even lower).
Julian (CL400) and (recently) TommyL have written very good and detailed reviews in this amp board. You might want to give it a try. I use it, too, and totally dig it for the price.