Preamps for $300 to match with B&K st-140?

You should be able to pick up an older conrad johnson tube pre (like a pv 1 or 2) or in ss, a mccormack micro line drive.

I 2nd the B&K Pro10mc. I may be biased I presently have one for sale.

Sorry, I have to disagree with the passive and AI recommendations. The B&K ST140's rather low input impedance does not make it an ideal candidate for passive or high impedance out-put preamps. I tried a couple of passives with the B&K and didn't care for the combination. The B&K Pro 10 could be the ticket. The B&K ST amps can be a bit mushy in the bass, becarefull not to overdo it with preceeding "warmth".

Look for used Forte preamp. I know the Model 2 will work very nicely.

Happy hunting.

I am useing a Parasound 850 with my B&K ST-140 right now in my den system and it sounds good. The Parasound has a phono section also and they can be found for cheap used