Fishcall- I used to have a B&K EX-140 (the early dual-mono version of their popular ST-140). I did an A/B to the ST140 at the shop I bought it from (Singer in NYC) and prefered the dual-mono by a slight edge for overall detail. The ST140 was VERY similar though. It was indeed very warm sounding and I did enjoy it. ST140's are easy to find and relatively inexpensive. All that said, if you are looking for "warm" why not got straight to the epicenter of warmth; get a tube amp. Lets see, you have $500-800 for the amp and another 500 for a pre? That's up to $1300. At that price you could buy yourself a great little integrated tube amp like a Jolida 502B putting out 60 watts of sit-by-the-fire warmth which should be plenty to drive most speakers. Heck your Studio 40's are 91db efficient...you could drive those to very satisfying volume with a Jolida 302B or an Audiomat Arpege! Any of these would top anything I've heard in SS at that price range for all around musical listening pleasure. If you have to stick to SS I think Plinius also makes an integrated amp in that price range used, but I've never heard it...only heard tell that it has warmer sound to it.
Good luck.
Marco
Good luck.
Marco