I'm one to get caught up in specs.. S/n.. Thd... Damping... Freq range...
Not really a good idea, as most of the time the differences you see are actually meaningless to how the amp will perform with a certain speaker, unless they are not within the range of what would be considered for quality equipment. Sometimes a very low Thd is achieved by using a large amount of negative feedback resulting in poor sound quality.
Good dynamics in the low end at a moderately loud volume will definitely require excellent power. I'm sure a Musical Fidelity A300 would have no problem, if you can find one. They rarely come up for sale, and will sell quick if not priced too high.