tmsrdg,
This is an old memory so forgive any misstatements.
I remember talking to Jim and Tom about their design work on the CS5 Loudspeakers. One issue, and a large one, how to pull the amount of current from the amplifier to adequately make the bass come alive.
The speaker had a stated bottom of about 22Hz as I recall. Jim said that they decided that if the impedance dropped enough, that that would pull the amount of current needed to adequately fund the bass. (just as the 3.7 drops in impedance in the lower bass) After the speakers were finished, he and I had dinner and Jim expressed his disappointment in the published specs of the big boy amps versus the reality of their capabilities in producing power into diminishing resistance. It seems that they were not nearly as powerful as claimed.
Back then, Gryphon, now a powerhouse amplifier, was woefully inadequate in playing program material on my CS5's at even moderate levels, with music having deep bass.
As Jim said, 'Every solve creates another challenge', or words to that effect.
So, tmsrdg, I'd check a review or two on your amp, I'm thinking you're right about the congestion issue. Possibly they don't rate their amp into 2 ohms is because it doesn't do well. Many don't.
Best,
Larry