Dipole Asymmetry

I agree that is pretty close to the rear wall. Solutions would be acoustic panels from GIK Acoustics.

Also, put a panel between the speaker and the rack. It won't be ideal, but much better. :)

imgoodwithtools

I am considering purchase of a pair of Martin Logan Summit X speakers. In my room, I am somewhat constrained for speaker placement. I could place the speakers about 3-4 feet off the front wall. My main concern is my audio rack would be placed directly behind the left speaker, while there would be nothing placed behind the right speaker

If this is your setup, there's really no good reason to be considering dipole speakers, imo. Yes, there are things you could do to limit the effects of the constraints you face ... but to what end? Your space is simply better suited to a more conventional box speaker system.

Since no one this far has said Aw, shucks, just put those speakers there and they'll be fine, I must assume there will be audible differences channel to channel. I suppose the magnitude of those differences would be open for debate. I think Cleeds may be right, in suggesting a more conventional speaker design. 

And why would I consider these speakers with my room constraints? Because I want to play, Dammit! Lol

If you have a turntable, putting it directly in the line of fire could potentially cause a feedback issue. 
IMHO, to get the sound you are paying for at those price points you need absorption behind the dipoles, even more so if less than 5' distance.

If you can't do that you could try floor standing absorbers that go right behind the speaker. Warning, they are big, ugly and rare but Sound Lab makes a model and I believe there are DIY versions online. 

The best solution might be getting a longer set of interconnects and moving the rack if possible with just the amp(s) near or behind the speakers. Cheers,
Spencer