Audio Research versus McIntosh tube amps: anyone experience or compare both?

You have very nice systems.

Before trading amps, have you tried moving the speakers closer to the back wall / corners to reinforce the bass?

The ARC and Mac amps are very different. The Mac’s are heavy bass / midrange with a notable lack of detail / treble, and the ARC amp is detailed, with good midrange bloom and realistic bass as is only achieved by a really good tube amp. Especially given all the ARC equipment you own, you must try a ARC amp. I used Pass amps for decades. The first time I put an ARC amp in my system that was the end of my history with solid state amps and Pass (as great as they are). While the bass slam is attenuated, the bass becomes nuanced and realistic. There was no going back for me.

ARC and Mac amplifiers have completely different sounds. You need to hear them for yourself.

I agree with @cleeds 

In particular, how they handle  the upper midrange and treble is very different, and also different for vintage AR vs. current.

I'd suggest Ayre and Luxman to be on your short list, as well as Parasound.

I haven't listened to ARC amplifiers. I prevously used McIntosh MC275 MK VI and it lacked details and bass. It was weak. If you want dynamic, you won't have it. If you simply want tube warmth, it may work. Good luck!