A/B comparison McIntosh MC275 MK IV vs. MC275 MK VI

I have the mark IV and after many different tubes in this amp I have found that it sounds the best in this configuration.  V1 Mullard long plate Square Getter or Telefunken smooth plate in V1, Telefunken smooth plate V2 and V5, RCA triple MICA 12at7WA V3, V4, V6, and V7.  Vintage Tung Sol 6550.  Tried the Treasure tubes and found them a bit on the soft side for me.  YMMV.

I've owned both the IV and the LE (50th anniversary Mc275, virtually identical to the VI except for cosmetics).  The LE and IV have the same basic character, but the LE has deeper and tighter bass as well as more extended, cleaner high frequencies.  I ran both amps with the same tube set and got the results described above.  Hope this helps.

Sheesh guys, I retubed my MC275 Mk IV because of bad Chinese stock tubes as soon as I got it due to a problem.  I’m using Genelex KT88s from the 60s NIB matched quad and rca 12at/ax7s they appear to be black plates. I’ve got 180 hours on all tubes now.

My MkIV has incredibly hard hitting tight bass, outstanding mids and the highs are amazing.  I’m running the Mac new reissue C22 and driving University Sound 315C series 200s!  With this tube compliment and the rest, I’d say there are few amps that could touch this one, whatever mark number they are!!

I agree