[jpgr4blu]

Hi Charles:
We have dueled in the past. You can defend Mac to the hilt. Nothing will convince you that they do not make the best amps on the market. I have related my experiences with the 2 brands having owned and heard both for years with various Wilson speakers. Most notably, Mac obscures detail that ARC reveals-- and not in a sharp or shrill way. Mac is warmer and softer--some say due to the use of extensive extra extensive wiring in the autoformers which obviously has pluses and minuses as a Mac feature.
You present theories as to how the ARC Ref 160m amps cannot properly drive the Alexia2s. I suggest you talk to the people at Audio Research who have that exact match in their listening room as well as the dealer who decided to make the first public presentation of the Ref 160s with Alexia2s at an audio show which received rave reviews form a number of people including those who work for Wilson. I suggest you use your ears to make any comparisons rather than measurements. I also suggest that you read Ken Kessler's review in HiFi News and Record Review and the Stereophile review of the Ref 160s both of which were done with Alexia2s and both of which were outstanding (HiFi News more so --last sentence of review---"I suffer no hesitation in judging [the Ref 160ms] one of the finest amplifiers I have ever heard, regardless of price.")
So you can theorize why Mac works better with Wilson than ARC based upon your reading of amplifier and speaker specifications. But I believe careful listening is more important. My ears say ARC. Your ears may say Mac. We will continue to disagree. And that's fine with me.