Since I just finished converting a SRM-323A over to 240v I though it would only be fair to take one for the team here test it with the SR-007A. I can safely declare that it isn't really good at driving them not that couldn't be predicted. The extra bass bloom helps by covering up the true lack of extension and the sound is rather balanced but lack all the drama I know the SR-007 can deliver. The SRM-1 Mk2 PP is a rather better amp, even though it looks like shit next to the very purdy newcomer, with more extension, balls and HF sparkle.
In other Stax news, a new SR-Sigma Pro 404 has been born and I can confirm that the original SR-Lambda drivers used uninsulated, etched copper plates for stators. One sett arrived with a failed glue on the a driver so I split it open for a peek. Very simple construction and no wonder Stax has made them by the tens of thousands and still do.