LTA MicroZOTL tube upgrade

@itball I checked Mullard CV4024 out and their other name is M8162 whereas my current tubes are M8161. I am just wondering if the difference between them can be bigger than 1 digit :)

I have done essentially minimal tube rolling. The original tubes in the L2 were my baseline. I upgraded to the Ray Select and the Gold Lion. I liked them. With the L3 upgrade I have only used the Ray and Gold Lion. I suppose I should explore a bit. The previous posts provide a starting point for my exploration. Thanks.

I have an LTA MZ2 (late edition)

I’ve tried NOS RCA 12SN7 and 6SN7, Tung Sol 12SN7, Sylvania VT231, and GE 6SN7GTA, from Brent Jesse. The RCA 6SN7GTB (also from Brent Jesse) were the warmest and the RCA 12SN7 very similar. The Sylvania sounded very holographic but a little bright. For whatever reason, the GE tubes sound best with my current speakers, although those may change soon. 

The good thing is that tube rolling really pays off. Every change was very audible and significant. Just have to listen. 

I have the Level 3 microZOTL. I’ve used the stock GE 12SN7’s and Mullard 12AT7’s, and the Ray’s Select tubes sourced from Jacob. What I’ve found as the best combination for me so far: Amperex Holland 1960’s medical grade red tip 12AU7, and Ken Rad VT231 6SN7, both available at the time from Brent Jesse. 

In my situation, I needed a little less gain from the preamp. The options were to use the -15 dB gain switch in the menu, or switch from 12AT7 to 12AU7 tubes. I found the Amperex Holland 12AU7’s to sound better than the Ray’s Select plus the gain switch. 

The Ken Rad VT231’s have a very holographic presentation, and good tone throughout the audio band, from solid bass to airy, directional highs. 

@gabriel123 the M8161 seems odd to me, although I am not a tube or electronics expert. That tube is not an AT7 and not even the same type of tube in general (it's a pentode). Is it possible the label is faded or wrong?