Went ahead and did something.

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Mar 10, 2021
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Setting it up tomorrow. MC257. Pushing CLS ii's and a Logos center.
Nice, congrats!

So only going to use 3 of the seven channels?
Yes, I am going to use the LF, C, RF channels to maintain the higher 250w.
Ah cool, I'm not familiar with the Mac lineup, nice to see some flexibility in their multichannel offerings.
Very nice! I'm also a fan of McIntosh with ML. Just curious what led you to choose the 7-channel MC257 over the 3-channel MC303?
Set it to 4 Ohm, as the panel will dip to 1 Ohm in the Highs.
It's my understanding all setting it to 4 will do is throttle down the Vcc+ and Vcc- rails, decreasing the amount of power that can be delivered to the CLS, which is absolutely what you don't want. I may be wrong. I'm open to enlightenment by someone more familiar with a/v receivers. But in my opinion those speakers demand a serious power amp, which most avr's are not--precisely because their impedance visits insane magnitudes and phases.

If you're using tube amps, on the other hand, use the lowest impedance tap available, usually 4. My experience with CLS II's and tubes (Latino M125 monoblocks) has been poor, for the above reason.

But I see now your a/v amp is a Mac, which may cause me to eat my words about avr's. Is it one with an impedance matching transformer, or autotransformer? In that case, definitely set it to 4.
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Why is that? Why doesnt the wattage increase as the resistance goes down, as with most amps?
McIntosh amps are built differently. The higher models have Autoformers and taps down to 2Ω. The amps without Autoformers have something called Dynamic Power Manager, but I can't find info about how it works.
This amplifier sounds outstanding. I had previously been running a couple of outlaw monoblocks that just couldn't feed the CLS's enough sauce. Significantly better depth, soundstage, and of course the power.
Ok, so I replaced the glass that was cracked on the Mac. Crash course on my own since there are no instructions or tutorial. Took about an hour.

Got my height speakers reinstalled....Ran the Audessy through my marantz 8012 I use for my subs, and surrounds while using the Mac for R/L/C. 7.2.4 running, all ML speakers and subs. Sounds outstanding. Very pleased!!!!