Upgrade preamp?

Cayin SC6 dual mono @ $1500, best bang for the $

Brother, if you've got that kind of budget(2 big Bryston amps and then up to 5K for a pre)  you should be going straight to a high end audio shop that carries the Maggies and amps/pre's  that complement them.  

The Prima Luna Evo 300 and 400 series preamps have I believe a output impedance of 256 ohm’s. They will work well with any power amp. Sound fantastic too...

@mvrooman1526 

good luck, and i am happy to help with ideas

i have a cj et5, it is a brilliant piece....  if you get one, let me know, i can walk you through some useful owner tips around tube longevity

herron's preamps are absolutely in the same class, as i understand it... i have never ever heard of a herron owner say anything but wonderful things about the sound and the man/company behind it - herron is a smaller shop, doesn't get the press and PR... but absolutely beyond reproach...

@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