Autoforms in Mcintosh amplifiers give the end user the option to match low impedance curve speakers to the amplifier autoformer transformer and be able to operate the amplifier safely. As far as sound quality with Autoformers thats a whole other debate on AK you can read about.
I think matching a speaker to an Mc autoformer amplifier becomes a little more experimental for optimum sound. You need to spend time taping your speakers to the different terminals and listening for the best results.
I have heard of some owner bi-wiring in this example - taking two of the four speaker wires, taping to the 4 ohm terminals/com & connecting one set of terminals at the speaker - taking the other two speaker wires, taping them to the 8 ohm terminal/com & connecting to the other set of terminals at the speaker. I only read about this and I would get more guidance from Mcintosh before attempting this.
Autoformers add additional cost to the amplifier. I think you would be better off putting more $ in clean power than having an autoformer type power amplifier. JBL was never know to build low impedance speakers and if anything were always very stable and built for gobs of power.
