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!