McIntosg 7270 VS Meridian 557 vs D-125 AR

I think the ARC amp will have great difficulty driving the Extremas.

I've owned a bunch of 7270s. This is a workhorse of an amplifier and I wish I still had a few. About 10 years ago, I built an audio switch box so that I could sit in the sweet spot and compare the sound of two amplifiers in real time (gain matched of course). It just so happened that the amplifiers in the room the day that I wanted to try out my new toy were a McIntosh MC7270 and an MC225 (the much revered 7591 based stereo tube amp).

After carefully matching gains, I sat down to listen via a pair of B&W monitors. [The source was a Pioneer PD-T07 (still got that) and a Mc C29 preamp.] When I switched between amp A and amp B, I could not tell a difference. Naturally I thought my switch box was not working properly and I checked all the connections and tried again. Still no difference . . . hmmmmm . . . I turned off the MC7270 and the audio went dead silent. I switched back and the MC225 was working like a champ. Switcher worked fine!

To my surprise, I could NOT TELL the difference between these two amps on anything I played the rest of the afternoon - short of music with extremely low bass. I guess that says all I needed to know about the MC7270!

Good luck.

Having a 7270 now for 4 months driving Merlins and it sounds great!FYI,good luck,Bob

Another 7270 owner here.

It's common to see SF owners using Mac for power, I would say they have good synergy together. As mentioned above, the 7270 is a workhorse, I've driven some large multi driver speakers, planars, and also a pair of speakers rated at 2 ohms, it's never flinched.