Been away for about a week...... could not play my amps as loud as I normally do since I had guests on Vacation. What I like about the Mark V, I can get the gain saturation at a reasonably lower volume level even with the 90W power. I also wheeled over the TC-50 from the studio (have it on a vert 212) and it is much louder than I expected it to be. Running the Mark V with combo and 1x12 speaker.
Considering how well the Mark V90 does with general 12AX7 tube swaps, the side effects will be similar with the AT in V4 or V6. Still the 5751 had merit when using long plate AX verses the medium plate (tung sol, Mullard CV4004, or even 7025. The ECC83s short plate JJ (Mesa) tubes definitely can spice things up a bit as well. It is all good.
Considering how well the Mark V90 does with general 12AX7 tube swaps, the side effects will be similar with the AT in V4 or V6. Still the 5751 had merit when using long plate AX verses the medium plate (tung sol, Mullard CV4004, or even 7025. The ECC83s short plate JJ (Mesa) tubes definitely can spice things up a bit as well. It is all good.