@joeinid
The MicroZOTL Preamp does provide more depth of sound stage. More details, probably because of less noise and as quiet as the MZ2 is that's saying something. The refined power supply and ceramic board aids in the quiet, black background as I understand.
I have discovered that tube rolling 12SN7's can make some drastic changes in sound. 6SN7's can also be used by changing a jumper on the board. I found NOS 12SN7's to be less expensive than the 6SN7's. I found out using 12SX7's gave me the biggest sound stage. I also found that Tung Sol VT99 and National Union 6F8G when used with adapters, were the most dense, dark, meat on the bones sounding. These results were when rolling with the MZ2. I have not started extreme rolling on the new preamp like I did with the MZ2.
I live near Linear Tube Audio so I will drop in from time to time and see what new things they're working on. They have been swamped with orders for the new preamp and behind in production because of it's popularity.
Lance