Preamp selection advice please

So I would like to start my next preamp project but can't decide between the Mezmerize or the B1 Korg.
I currently have a B1 and a Dodd tube buffer driving a F5 or Folsom's chip amps.
I think I will be building Folsom's new 7293 version as well.
Speakers are currently Hawthorne Audio open baffle but soon to be GR research open baffle with a separate low frequency section.

Which preamp do you think best suits my system ?

I can't seem to find any comparisons of the 2 preamps on the forum.
 
The Mezmerize is a B1 buffer that is directly coupled, with no coupling capacitor, and improved power supply. It would sound similar to the B1 that you have already.

The B1 Korg is a preamplifier with voltage gain. It has a buffer stage in front of and after the Korg tube triode stage that provides the voltage gain. The differences are the B1 Korg provides voltage gain and the Mezmerize does not, and the Korg triode stage provides a good dose of second harmonic distortion, which the Mezmerize does not.

Your F5 is a very clean low distortion push-pull amplifier, and what distortion it has is predominantly third harmonic. The B1 and Mezmerize also have very low distortion. The B1 Korg on the other hand has a good dose of dominant second harmonic distortion which will impart a sound that most appreciate.

However only you will know if it is to your taste. But you can read about it on the B1 Korg thread.
 
One of my early setups had a Bottlehead Foreplay preamp (lots of gain) into a 55W AKSA (lots of gain). That made for a super hair trigger volume control that I absolutely hated. And just throwing away tons of signal to ground with the control at about 5%.