My dad had a original MC275 & C22 from 1964. Also a McIntosh MR67 tube tuner, Garrad 301 turntable, and Klipsch Cornwall speakers.
In 2006 I decided to redo my audio setup with 2 separate systems: tubes for digital & solid state for analog.
While at the MAC dealership I had auditioned a few MAC amps, one was a 275 in both stereo and 2 mono. The 275 hadn't changed its sound over the decades at that time of audition. The 275 still had not much bass whether single stand alone stereo mode or 2 mono running as stereo.
The sonic attributes of the 275 still present with excellent mids and treble.
After auditioning the MC2102 it became apparent the the 2102 had the same mids and treble as the 275 but had a good deep bass response as well.
Some people like their 275 paired, as well as for the 2102. I found no sonic advantage in doing so for myself so I chose the 2102 for my digital playback system & a McIntosh MA6500 for analog.
My final assessment of the amps regarding the 275/2102 is that they are excellent basic amplifiers in a tube design. Careful attention to speaker choice is necessary in order to maximize the potential benefits of their sonic attributes.
Same principal regarding the MA6500 integrated amp. I didn't like the MAC preamps too much but the C22 is the exception because of its phono section which is pretty good but not excellent.
In the end I chose a CJ preamp for my 2102 after auditioning various preamps for about 4 years.
A excellent basic amp needs a excellent basic preamp. Before the CJ preamp I was running my McIntosh MCD500 directly into the 2102. I wanted a FM tuner so I needed a preamp.
Sorry for the rant but your initial photo of the 275/C22 brought back many memories of growing up.
Just my opinions.