Thoughts on adding a McIntosh C12000 preamp to my AVM90 Home Theater Processor....

My opinion is that , with the quality speakers that you have , the sound improvment for your two channels  listening would not be subtil.

Home theater  processors and receivers are not the best for two channels listening.   
 

My Dad just did something similar. He had an Anthem AV receiver and 5 Sonus Faber speakers.

Out of the blue he said " I always wanted a McIntosh" I said "Do it ! "

He picked up a new McIntosh MA8950. I set it up with the Passthrough that I am assuming the 12000 has like the 8950 and 9550. It is slick. You need to wire a trigger to the Mac from the Anthem trigger out. When you do and select the input you have the AVM left and right front connected to it turns on the Mac and puts it in bypass. You are only using it’s amp section. Then when you power off the AVM the Mac returns to its previous state or to its last input. Or off if you used bypass last. Its really slick and allows seamless integration of stereo and HT

He kept the center and surrounds but upgraded the mains to Sonus Faber Electa Amator III. It is a killer setup with hifi and video sources.

Thanks @oddiofyl - did you and your dad hear a noticeable upgrade between the 2 channel audio of the AVM and the C12000??

@whitesarhara, I have a C12000 that I use for two-channel listening and a separate Athem pre-processor for Home Theatre.  For a while, I ran a trigger from the Anthem to the C12000 bypass and connected the front speaker out of the anthem to the C12000 channel 6.  It was perfect but I decided not to use my more expensive amps and speakers for home theatre.  I ended up purchasing the new Martin Logan on-wall speakers and an inexpensive 5 channel amp.  Best decision for me. 

My two channel system consist of: VPI Avenger Reference, MCD12000, Aurender A15, C120000, MC451, B&W 801D4. 

Night and day with movies using the Mac and new SF.    And now 2 channel performance is in another league