I use an RBI for a preamp in my rig and I think it's absolutely great. We did a fair gig a few weeks ago and numerous people came up to the soundman during the show and complimented on how good the bass sounded. Several guys asked me what I was using after the show and I told them, my old Carvin LB90 bass, Sansamp RBI, EBS MultiComp compressor(in the effects loop of RBI), Crown Macrotech 1200 amp and an EA NL-210 cabinet, nothing very fancy.
The RBI took me a little while to get really figured out too. For me the best settings are pre 50%, Blend 100%, Bass 50%, Mid 35%, Trebble 35%, Presence 0%, Level 70%.
Also, I found it better to run my Crown amp using the XLR output from the RBI(quieter) and then I use a Radial DI box to feed the PA from the normal Sansamp output.
I've used this thing for over 2 years now with no problems what so ever but my question still is, HOW DOES THIS THING WORK? How does it do what it does? Ever look inside of the RBI? There isn't much of anything in there!