A good match preamp for B&K EX-442 Sonata amp?

I just noticed that my Harman Kardon AVR 635 receiver has separate stereo preouts (multi-room) to power an external amp. So, besides trying to find a good fit for my just purchased B&K EX-442 Sonata amp, how well will the HK do as a preamp?
TIA for any responses.

How much money are you budgeting for the preamp? As for the Receiver, I've tried using a few different receivers as a preamps (Yamaha, Denon, Sony) and while the addition of an outboard amp was an improvement, the receivers really didn't perform wellas preamps, and it wasn't hard to find a standalone preamp that out performed them in a big way. This may not be true for your HK, and it's certainly worth trying it.

Do to finances, I figure to spend about $150-400. Since I bought a 20 year old amp, I'm not opposed to same for preamp. I am more concerned with matching the (hopefully) warmer quality of B&K Sonata. Eventually, I may end up back to tubes!

I haven't owned or heard the EX-442, but did/do have many other B&K amps, including EX4420, Ref 4420, St140, and currently about running M200 Sonata monoblocks. I've tried many preamps and haven't really found any that didn't work nicely with the B&K's. For the lower range of your budget you can probably find a B&K CS-117 (I owned one of these) or CS-115. The CS-117 is quite nice, especially for the money, and can be found with Phono if you need it. A Pro 10 MC may be a small step up in $ and perf.
Other than the preamps I currently have/am running, I probably liked the Exposure RC21 best - it was definitely warm sounding, the problem is the RC21 may be hard to find under $400, but it may be possible to find on just over that $. It's a line stage only. The only downside of the RC21 is it has a quirky remote , and a high noise floor. There may be some earlier Exposure pre's worth trying too.
I'm currently running the Dared LS2000a Tube preamp in one of my rigs. These can be found for $300 or so used, and with the right Tube complement it's really pleasing. It only has 2 inputs however . . .
These are the preamps I'm familiar with, and I'm sure there are many others that will do nicely in your budget.

BDgregory, thanks much for your help. I may look for the tube preamp as I'm only intending to use my Nad c542 cd player for this setup.