McIntosh MC 275 Mk IV or V with Harbeth M-40.1?


I've had my Plinius SA-102 for longer than any previous amp (almost 3 years) and have been very satisfied with it's reliability, musicality and build quality, but I'm very intrigued with finally trying a classic tube amp.

I listen to classical, jazz, vocals & acoustic rock at moderate volume levels, so I'm thinking the 75 WPC of the McIntosh MC 275 (mk IV or V) would work fine in my 15' x 21' x 7' basement set up. The Harbeth M-40.1's sensitivity is 85dB/W/m, 6 ohm nominal. Suggested amplification: >50W (Stereophile's review of the M-40.1's noted excellent success when driven by a 35wpc Shindo push-pull amp)

I've researched other tube amps from Rogue (M120's & 150's), VTL (ST-150), Manley (Snappers), Cary (120S), Audio Research (VT-100 MK III) and Quicksilver (V-4's). Ultimately I'm leaning heavily towards the Mac MC 275 (Mk IV or V) due to its not being a monoblock, it's a classic unit with excellent build quality and good resale value, and it's known to be reliable and is easy to bias.

Preamp is an Aesthetix Calypso with NOS tubes and my sources are digital and FM.

Comments from those experienced with later model McIntosh MC 275 and/or Harbeth M-40.1's would be appreciated.

Thanks - Paul

128x128pdreher
Paul, please let us (me) know the results of the GL KT-88 power tubes you plan to use in the Mac 275. I am also considering changing my power tubes but not sure about Gold Lion (re-issue) or Penta??

Tks!

Rick (RWD)
Rick - On Neil's (Nsgarch's) advice, I plan on sticking with the stock Svetlana KT88's for now (due to limited funds), but have NOS RCA triple mica black plate 5751's and Sylvania tmbp 6201's I purchased from Neil that I will experiment with this weekend when I set up the MC275 mk V for the first time :o)

I may be in position to try the GL reissues in a few months.
Tom - so far, so good. I'm currently listening with all of the stock tubes to get a feel for things, but have the NOS RCA 5751's & Sylvania 12AT7's ready to roll. Surprisingly, the amp sounds really, really good with just the stock tubes... a very pleasant surprise ;o).

The MC275 with the stock tubes is lacking the detail & refinement provided by my previous amp (Plinius SA-102), but it's noticeably more musical, natural and robust sounding without being in your face... I'm really loving it! Will be interesting to see if the NOS signal tubes take the sound to a new level.
Hope it gets even better for you. Does the drop off in power seem to be an issue with the new amp?