The nuforce sounds interesting. For about $200 more you can get the 50WPC integrated, It has no balanced outputs, but being an integrated, I could get rid of my monoblocks and simplify my rig. I don't really want to part with my amps, though. Luminous Audio sounds like a good idea. I think I'll email Tim and see what he has to say. I also noticed that Goldpoint Audio makes a small passive pre with two balanced outs. I could use an adapter to convert one to SE to drive my sub.
Thanks for all the replies,