Recommendations please for good, affordable pre-amp for system?


Hi All, 

I'm configuring my first system, and have so far acquired the speakers (Thiel 3.6) and amp (Bryston 4B SST). I believe I need a preamp to complete this (and I believe only a preamp, right?). And I'm hoping you can give me some leads, information, and recommendations.  It's a 2-channel setup, and while it would be nice to add some HT capability in the future, I'm seeking as pure a sound as possible.

Some things I've looked at are Theta Casablanca, Bryston 0.5B, and perhaps for future upgrades, model Rotel RSP-1582 and Marantz AVR8802 -- although I'm concerned that those latter two, while brining nice features, will work to molest the signal.

Prime listening will be CD, with some lossless Network-attached storage, and Airplay with Tidal or otherwise Internet radio.

Thanks for your recommendations!
donzi
Thanks hanfrac, Nice unit! I found it interesting that you felt the sound better out of this Bryston than a tube preamp. I had understood that tube usually added warmth to the system (a bit of a concern for me, as both my speakers and amp are known to be "accurate".) I ended up getting this unit, but had a bid in on a Bryston 0.5B. I didn't chase it aggressively, as I knew that preamp was already on the way. But, especially in light of all of that, your experiences are fascinating. 

Part of the reason I went with Bryston is that this is what the people at Thiel recommended for those speakers when I called them. For sure, this is all subjective, but as a new member of audio, I figured theirs was good advice to get. But then again, I'm told that they're both bright.

Another preamp I'm considering is this one, based on a recommendation earlier here. For sure, this is a future upgrade; but the idea of building my own simply fascinates me. --And, I was hoping, the tubes would add warmth. Perhaps not always, based on your experience. And perhaps as the Thiel rep said, Bryston/Bryston might be the way to go with amp and pre. Bright + bright + bright. Who knows, maybe that's the way it was designed to be.

I just picked up the speakers yesterday, and none of the rest of the stuff is here yet. So I'm anxious to plug it all together and see what I have -- and begin the process of hearing and listening. And perhaps, fine tuning as time goes on. Someone else here also said some wonderful advice, that, in his opinion, the preamp was a harder purchase than the speakers. Certainly this is not something that I can chase with continual purchases to try it. So, thanks again for the recommendations and thoughts!
I talked to engineer at Bryston and he said BP-6 thru- 20 series pre's were all basically the same .
But not BP 0.5 or BP 1, I would presume? Good info. Would you imagine that staying within a brand is generally a better, more compatible way to go, in terms that they know what they're trying to achieve end-to-end?
@jond , Donzi bought the Theta Digital Casablanca 6-Channel Preamp Processor.