I just quit from tube amps, but got quite a few 6sn7 tubes unsold in my collection. TBH, I was not very impressed by Lyr 3 with stock tube. For curiosity, I bought two Lyr 3 for side by side tube comparison. I have a Schiit Yggdrasil, so that I am able to fed these two units at the same time via rca cables.
I used to believe that tube rolling won't make much difference on hybrid amps, but I changed my mind. Different tubes do make significant difference on Lyr 3. I believe most ppl will be able to pass AB test.
I have tried the following (too bad I forgot to take notes, so all impressions are based on my memory),
1. GE 7N7 tall bottle: closer to solid state sound, the high can be a little sharp but not harsh yet.
2. Sylvania 6SN7W: I am a bit disappointed on this one. It is on the warm side, but its bass is a bit muddy. Overall, it sounds quite similar to the stock tube to me. Not worth the expensive price IMO.
3. Tungsol Black Glass VT-231 round plate: this is my default tube for Lyr 3 now. Very balanced sound, good on almost anything. It's not bass heavy but very satisfying
4. Tungsol Black Glass VT-231 oval plate: very similar to the above
5. Tungsol VT-99 Black Glass round plate: I really like this one on Lyr 3. Very deep soundstage, lussy, bass is a bit heavier than Tungsol BG VT231.
6. Mullard CV1988: very sweet mid and high, airy, but bass light
7. Schiit LIIST: it indeed sounds more like solid state. Faster and more accurate.
8. Raytheon VT-231: transparent, airy, good soundstage
9. RCA VT-99 Grey Glass: Warm, good all around
10. UN VT-231 Black Glass: this is one of my favorites on Lyr 3, similar to TS BG VT231, but better clarity and low end, very engaging.
After replacing the stock tube with something matching my taste, Lyr 3 is now very enjoyable. It loses to my Niimbus 5 Pro on almost anything, but it is only at 1/12 of the cost. Plus it sounds different enough with different tubes, I decide to keep one for myself.