McIntosh MC275VI vs Rogue Audio Stereo 100

I have not used the Rogue, but did have the Mac.  It definitely benefits from upgraded tubes, especially the small signal tubes.  I also used the GL KT88s which made a smaller but noticeable improvement.  
 

I have since moved to Pass 30.8 and like others have mentioned, it makes the Mac sound a bit muddy.  Definitely hearing more of the music without sacrificing musicality.  

I owned a 275 and was very underwhelmed by it.  It sounded plain and very ordinary.  Absolutely nothing special at all.

rogue! more refined, more open, and works cooler

From what I've read the 275 does benefit.  The one i listened to had Gold Lion KT88 and stock tubes everywhere else.  

does the 275 benefit from NOS tubes?

The Rogue definitely benefits from NOS tubes. 

The 275's I've heard have a "classic, romantic" tube sound that most people think tubes sound like. Great for Jazz, classical, acoustic, etc. However, if you listen to lots of modern music, especially music produced with drum machines, synths, etc...I'm guessing the 275's will have a dull, muddy presentation. 

Btw, the Rogue Stereo 100 had NOS Millard tubes. It is a necessary upgrade. The stock tubes are rather simple and dry sounding 

I tried both amps on Klipsch Cornwall IV speakers and I didn't like either one better than a Van Alstine 600R hybrid amp with NOS Mullard 4024 tubes.  I agree with the samzx12 and pani regarding the MC275 VI.  It's warm and lacks clarity.  I thought I would like the McIntosh best but it wasn't to be.  The Rogue ST100 that I tried had the Dark upgrades.  It had more clarity than Mac but it wasn't a good match for my Cornwall IVs.  The sound with Rogue was definitely more SS sounding and it just wasn't relaxing to listen to.  The ST100 was my friend's amp and he agreed it wasn't as good as the Van Alstine 600R.  Ultimately, I purchased an Enleum 23R, 25 w/Ch that is better than all amps that I've tried to my ears with my 102dB sensitive CW speakers.  I still have the 600R and I use it for my more power hungry Sterling Broadcast LS3/6.

I also had both MC275 Mk6 and Rogue ST-100 in my setup driving Tannoy Turnberry SE speakers. MC275 is nice but it is warm and lacks clarity. If you want a warm sounding easy sound, go for it. ST-100 on the other hand is a nice and proper neutral tube amp. It will not sound like SS but it will also not remind you constantly that it is tubey and rounded. If you notice, it is tube, if you don't it is nothing. Higher resolution and clarity than 275. It is one of those amps which will not sound out of place even in a $200k system.

Two totally different sounding amps. The MC275 is definitely a warmer sounding amp that has the classic tubey signature.  The Rogue has more of a solid state sound while retaining the tube magic. More like a Audio Research amp. My question is what are your speakers? Both amps are very powerful.  I've had both amps in my system pushing Sonus Faber Olympica iii.  I thoroughly enjoyed the MC275 but it was a bit too warm for the Olympicas. Otherwise a fantastic amp. I'm currently using the ST-100 and so far so good.