Upgrade preamp?

@georghifi, i read that you want to have a minimum of a 10x different between your preamp output impedance and your amps input impedance.

Yes 1:10 is mine and others min recommendation 1:50 better.
You’ve got to remember also that the source if tube is looking at a paralleled impedance combination of a passive pre10k plus the Bryston amp 7.5k, total seen buy your source is 4.3k load.

Cheers George

Rogue Audio RP-7.  Transparent, dynamic and silky smooth even with the stock new production tubes.  

Anyone have any experience pairing McIntosh preamps with Bryston amps?   Deciding between a C47 or sticking with Bryston and going with their BP26 preamp with external power supply.  

Anyone have any experience pairing McIntosh preamps with Bryston amps? Deciding between a C47 or sticking with Bryston and going with their BP26 preamp with external power supply.

I bought a used C47 some time back and, when it first arrived, I tested it in a secondary system which had a Bryston 4B-ST amp. It had no problem driving the Bryston and I actually liked the combination. I haven’t heard the BP-26 but found the C47 to be a tad richer tonally with slightly better instrumental separation, front to back, compared to the BP25.
The BP-25 had good detail and possibly a wider sound stage but all these differences were subtle. The characteristics of the 4B-ST, good and bad, were not masked by either preamp.