Mixed driver tube for Mcintosh MC275

Tzh21y, I did not write that one can simply pull off V1,

If one pulls a tube, most likely a series string of tube heaters will be interrupted and the amp will malfunction.

My experience is with a MK V version, other versions may vary. For example, on the schematic available on the internet (most likely MK I), V1 is essential. The amp will not play without it.

That's why I ended my post as follows:
I used to own an Mc275 MK V but I did not have access to an schematic, therefore I chose to be conservative and not mix and match tube brands.
I chose three Phillips Holland 12AX7s (ecc83) and four Miniwatt 12at7 (ecc81), all matched.

As you can see, I kept V1 in place.
Enjoy the music!

With balanced inputs, does MC275 combine the signal first and then split the phase for push pull output stage?

in my MC275 V with very good results. Musicality and instrument definition greatly improved with the Mullards over the stock 12AX7's. Also found that the amp benefitted from using Audio Research tube dampers on V1, V2 and V5. Tried the dampers on the 12AT7's and really didn't notice much of an improvement, at least not compared to the dampers used on the CV4004's.

I am using Mullard CV4004's in place of the stock 12AX7's in my MC275 V with very good results. Musicality and instrument definition greatly improved with the Mullards over the stock 12AX7's. Also found that the amp benefitted from using Audio Research tube dampers on V1, V2 and V5. Tried the dampers on the 12AT7's and really didn't notice much of an improvement, at least not compared to the dampers used on the CV4004's.

Cheers

I have the MK IV so maybe it is different