I need a good Preamp

I’d recommend looking at Coincident Technology’s linestage. These preamps don't come up on the used market very often for good reason.

Coincident Linestage (uses 101D tubes) $5,000: http://www.usaudiomart.com/details/649343645-coincident-statement-linestage-rare-remote-version-w-upgraded-tubes-and-pc-free-shipping-paypal/

Some reviews:
http://www.high-endaudio.com/RC-Statement.html
http://www.enjoythemusic.com/superioraudio/equipment/0410/coincident_statement_line_stage.htm
http://www.audio-activity.com/coincident-statement-linestage-in-english.html
http://www.coincidentspeaker.com/review_coincident_statement.html

Top level Luxman has gotten great reviews. I have their phono pre and like it very much. I would go listen to one.

I can highly recommend McIntosh C22. I've been running it in my system now for about a month and the transformation is amazing. Recommended in this year's Editor's choice Absolute Sound for what it's worth. 

<Krell dealer disclaimer>
Krell preamps work well with Krell power amps.  How about grabbing a Krell Phantom and upgrade to CAST to your 350 monos!  Yeah.  :-)  

If your inputs are to be as noted, you don’t need a preamplifier. Your hi-level sources all provide a line level signal that’s capable of driving any basic power amplifier (preferably with voltage gain ≥ 26 dB and Zin > 30 kΩ) to full output directly, without further boost. Only two functional parts will then be needed: (a) a stereo selector switch to pick the desired input, and (b) a variable stereo level attenuator to set volume. These two controls are entirely passive, and can serve as your basic control center. This minimalist design is simple, pure, and entirely optimal. No messy tone controls, because they mistrack and self-generate distortion. No balance control, because the source signal is already balanced. An accurate volume control, implemented as dual, fully calibrated stepped attenuators (not ganged “pots”), can precisely track and maintain balance at all levels.
There are numerous such devices offered. They’re popularly called “passive preamps” (no active components). My own personal pick is the Goldpoint SA4, specified with a stereo 10 kΩ stepped attenuator, from Goldpoint Level Controls, Sunnyvale, CA.: http://www.goldpt.com/index.html.