Pre-amp for MG3.6/Bryston 7b combo

Any suggestions for pre-amp from owners or listeners of MG3.X/BRYSTON 7b amp combination? I am not wanting to make a mistake. Local dealer suggests Theta CasaNova because of built in dac. However I already have a theater system and have no intention of using this for anything but music. I am not opposed to purchasing separate DAC. Budget is $5000 for Pre-amp/Dac. I have no problem with purchasing used equipment. P.S.-Dealer wants me to purchase Theta Dreadnaught in stereo or 4 channel Bi-amping instead of Bryston 7b. Ideas on that?
I agree with you that this should be a 2-channel system. With the 3.6 and bryston amp...what interconnects and speaker wire are you using...and you mention you have a transport already....these would have impact.. For what it's worth I have had 1.6, 3.6 and MG20...and have liked high-current solid state for the amplifier..and an excellent tube pre-amp...seems to be a good combo for the Magnepans.
I have MG 3.6/Bryston BP-25MC/2 Bryston 4BST/Bryston electronic crossover. I use HT ProSilway MK II and HT speaker wire. Bi-amping made a MAJOR improvement to my system in a room approx. 19+ X 28+ with a 14 ft cathedral ceiling (lg room) and there is more than enough power to drive the system to very loud CLEAN levels. I would recommend Bi-amping to anyone. Bi-amping with the 7Bs would be perhaps better but in my room somewhat over-kill, but..... If you don't use Bi-amp set up use bi-wire to MG 3.6 as that made a big improvement with only one 4B-ST. Better, I'm sure, with 7Bs.
Whatjd. I have a CD player now-no transport. I have been trying to buy a Levinson transport. However, a friend suggests I wait a few months to see if the sacd or cd-a format high-end manufacturers will come out with a transport that is digital out for those formats. The Maggies have been on order and should be in this month. I thought I would try different cables and speaker wires once the components are purchased. However, I would appreciate any suggestions. The Maggie dealer suggests Kimber speaker wires (an 8 wire version) and Wireworld Balanced connector (particulars unknown). Suggestions?