There is a reason why Class A is favored by top producers of amps, preamps, and DACs. It need not matter whether one speaks of transistors or tubes. It is not to waste electricity or to create monoblocks that need to be shipped by freight instead of a routine carrier. You can read the reasoning behind class A on a technical level at manufacturers web sites. To my ears, class A has a very dynamic, energetic, palpable, and 3-dimensional sound. There may be some good A/B equipment which is quite enjoyable, but class A is the real deal and not hype. I had an amp with a A and a A/B switch, and it was akin to going from mono to stereo.
My opinion is to narrow your choices down to 2 contenders, demo each in your own system, and enjoy. If you have not bought your Rockports, get your dealer to help you or at least work with you to clinch the sale. I would think your dealer would be interested in this question as well.