Thiel Owners

Batmanfan - I claim ignorance of what preamp Jim used for the CS3.7 development. He used the Krell FPB-600 and Goertz flatwire.

How he approached equipment, in general, was to work with the obvious allies in the business, those brands which would be demonstrated and sold with our speakers. They included Audio Research, Bryston, Krell and Levinson - I remember the Pass Aleph 0 that Nelson developed to drive our speakers well; there may have been others later or fallen through my memory lapses. There was never time to play with toys. Thiel generally borrowed and lent so that latest versions of those amp brands and our speakers were in each others' stables.

batmanfan - there are several discussions in the digital group of threads that could be helpful; my take is if you have more than one source (and I bet you do), DAC design continues to change and evolve, so if you want to maintain the ability to change/upgrade the DAC, you'd be better off with separates.  That being said, there are fans of some boxes that do both, but this does lead to some built-in constraints down the road.  The other question is the streaming part - again, one unit or a combined DAC/streamer.  With all things audio, cost becomes the biggest constraint.  

Batmanfan - I have been told that one of Jim's primary preamps was the Sonic Frontiers 2-piece gold unit. But I don't know if it was used for the 3.7s. I know that at shows we never mixed and matched pre and power amps, seeming poor form from an industry allies perspective.

batmanfan,

As you're keeping the 28B monos, I'd suggest you consider the BP17 cubed preamp.  IMO, it's a neutral preamp,  and neither adds to  nor subtracts from what is on a CD.  It does require some additional break-in beyond the 100 hours  of testing by Bryston.