Preamp for Classe CAP-150

Have a Classe CAP-150 integrated driving Totem Hawks, Sony Jukebox thru Benchmark DAC-1 as one source, Denon 2200 for DVD-A and SACD. Have heard the preamp section of the Classe is a weak link and was interested in experimenting with a good but inexpensive tube preamp to add some smoothness/air while maintaining bass "oompf" and control. Have heard good things about Jolida, Eastern Electric, Primaluna. Any thoughts on whether this would actually be an upgrade or any other preamp suggestions would be appreciated.
Ian, I am currently using two CA-150's as monoblocks through a CJ 14-LS and am quite pleased with the combination. Prior to this I used a Classe CP-50 and was happy until I tried the tube preamp. Also, I have tried the Benchmark in my system and was impressed but am more impressed with a Bel Canto DAC 2. Beware that the Bel Canto is going to be offering a newer version early next year. I am using Cardas Neutral Reference for interconnects and Synergistic for speaker cables. This combination has put the piano in the room. The only downside is the very bottom notes from a large pipe organ. Hope this helps. Steve