preamp upgrade suggestion around $2000

I have both the Don Sachs and the MZ2; both of them are outstanding bargains, but they are really different. 
The MZ2 is on the cool side of neutral, amazingly quiet, startlingly lifelike, super resolving and incredible bass. It is quite unique sounding, falling somewhere in between tube and solid state sound.
The Don Sachs is more romantic sounding, more holographic, euphonic, noisier, just a bit less resolving, bass a bit softer and rounder, and overall more in line with “typical” tube sound.

Of course, these are my opinions based on my system, my room, etc. Others may feel differently.

I should clarify that I don’t think the Sachs is a particularly noisy unit; just that it is noisier than the MZ2, which is a supernaturally quiet preamp. Kind of the same dynamic to my comment about the bass - the Sachs bass is good, it’s just that the MZ2 bass is tight and slams like solid state.

The Sachs is an excellent unit, but if OP is looking for something on the cooler side to balance out the tubes elsewhere in his system, I would probably steer him to the MZ2 out of those two units. 

I love them both for different reasons and on the whole wouldn’t say one is “better” than the other. They have different strengths and weaknesses, and I think it comes down to personal taste.

*Edited to correct that I’m using the Black Treasure CV-181 in my Don Sachs, not the same tubes as previous poster as I originally wrote.

@nwres thanks for the tip, I might give those a try.  I’ve tried to avoid going down the 6SN7 tube rolling rabbit hole, but if I’m being honest it’s probably only a matter of time.  And the MZ2 can use 6SN7 too.....