Help me with preamp choice.

Sonic Frontiers Line 1 or 2 is in your price range and are great pieces. BAT is nice, but don't think you can get one under $2K.

A descent preamp that do not colour the signal cannot be cheaper than $2k even used. The only way to get a great uncoloured budget performance is to get a passive preamp that will literally smoke anything under $2k. By getting an active preamp you will color the bright Krell even more. There are the following choices to your consearn:
Creek OBH14 - remote volume control/input selector; EVS volume pots(they're very inconvenient but claim to sound superb); McCormack TLC1 with buffered active tape loop; MicCormack micro Line Drive(has both active and passive outs); and finally Placcette that claims to be the best passive preamp with remote.
In order make a successfull setup with passive preamp it is essencial but not urgent to have your amp's input impedance >=40Kohm. If your amplifier has low input impedance 20Kohm or less you can acquire the Musical Fidality X-can tube buffer that will elimitate the impedance mismatch. It can be acquired for bellow $200 in addition to your passive preamplifier. It's more important to have a large enough output from your CD player wich I believe has enough.

Marakanetz, my amp has 47K input impedance and my sony book says 2 Vrms ( at 50 kilohms ) analog out. I have never used a passive pre before. Don't know if it is the speakers or the sony but the amp does not sound bright at all. I will do a search on some of your ideas. I have never heard any Placcette gear.

I believe that you should be OK with passive preamplifier. In my case I tried lots of preamps bellow $1500 but was only successful with passive setup with slight loss of dynamics but with great gain of transperency and naturality.

Tube- used- Sonic Frontiers SFL-2 - $1K-$1.4K

SS- New- PS Audio PCA-2