Bryceeboy, I went from the Soundlab A-1 to the Ultimate 1, and there was a big difference. However, in my case there were several upgrades on the Soundlab design in the interim, so my experience is inconclusive as to what did what. I agree that the two models being close is probably accurate. However, this would only be if the A-1 was ordered with the Ultimate upgrades, which include special wiring, posts, connectors, and toroidal transformers. Beyond that, the rigid nature of the steel frames should produce some performance gain, but probably not proportional to the difference in expense. The same question could be asked as to the differences in performance between the A-1 and the less expensive M-1. Each of these three Soundlab speakers, if equipped with the Ultimate power supply upgrade, are more alike than not. They share the same core, same diaphragm and radiating area. My excuse for buying the Ultimate 1, is that I love Soundlab, and having owned the others first, committed to their best model, knowing it suited me perfectly and that it represented my final purchase in a loudspeaker.