Personally, I think the Parasound P/LD-2000 is the best overall sounding solid-state preamp under $1,000.00 and even above! I have tried out many with my JC-1 monoblock amps, and it is clearly superior, with the JC-1's at least.
It is extremely dynamic, musical, full-bodied, open, and very extended at both ends of the spectrum, and has excellent imaging and detail. A bargain! I got mine for $450.00! Now, I cannot say or predict how the Parasound would match-up or sound with your Palladium II monoblocks or B&W speakers. I would highly recommend trying one out, however!
I have not tried one, but I have also read that the Odyssey Tempest is an excellent sounding preamp. They retail for around a grand, I think?
Hope this helps.