Would McIntosh Auto Transformers affect speaker sound?

Simmer. Sorry, your skin hasn’t been toughened up yet. I, like all the MAC fans have an opinion, sorry.  I reread his post to make you happy. Mac fans are very loyal but their equipment is not for everyone. I can’t say the auto former is the problem. Engineers might be able  to explain the benefits or weaknesses. If it sounds good to you, that’s all that matters.  

Speakers are rated in simple Ohm ratings. Most speakers impedance changes across the frequency spectrum. Music signals are a mix of many frequencies at once making for a very complex relationship.

Amplifiers manufacturers give you a simple ohm rating so you do not severely overload the amp. Say by running 2 pairs of 4 ohm speakers in parallel.

Speaker manufacturers give you a simple nominal ohm rating to help you select a suitable amp or which taps (transformer or autoformer) to run their speaker off.

I would agree that a transform will not affect sound staging, etc., however transformers are effectively coils, and coils have an effect on high frequencies. So wouldn't the introduction of a transformer into the chain cause some issue (be it phasing or whatever)in the sound quality in the high frequency range. Just asking.

In this rare instance I actually agree with AudioTroy. The reason Mac amps sound so warm with otherwise neutrally voiced speakers is the autoformers. The same goes for other brands’ transformer-coupled output stages. It’s essentially the complete opposite end of the short-signal path design spectrum. 

I can't imagine any good reason for using an autoformer in modern high quality solid state amplification.