The most tube-like preamp I have heard is the Audio Refinement Pre5. This is an incredibly underrated pre that has 5.1 ins/outs for multichannel sacd and a very nice remote. The sound is very SET-like, with excellent extension at the frequency extremes and superb resolution of detail. I'm using it with a VAC tube amp with fantastic results. You should be able to fine one used for about 650-$700.
