The B&K 10 series of preamps whether Sonata, pro or MC are probably the best of the B&K equiptment. All are neutral leaning warm and fairly accurate preamps. There are plenty of better preamps out there, but at their price, B&K preamps perform admirably. There is no doubt as Saki70 mentions that you can get more warmth in a tubed preamp, but as EVERYONE know, tubes aren't for everyone.
Dvdgreco, I do like my other suggestions better, maybe out of ignorance (I haven't listened to the big B&K's) but I'm told the big boy B&K amps are also quite good, warm and inviting, but much better slam on bottom than your current ST202.
Dvdgreco, I do like my other suggestions better, maybe out of ignorance (I haven't listened to the big B&K's) but I'm told the big boy B&K amps are also quite good, warm and inviting, but much better slam on bottom than your current ST202.