Just some idle thoughts about classD/SMPS. Would appreciate some informed input from those with relevant knowledge and experience. I was a believer but after trying various power amps I now have my doubts - not so much about class D - but about the switch-mode power supplies that (usually) feed them. I think it's all about having the headroom (and the power supply is part of this) to deal with the initial attack of a note. Class D/SMPS can handle it provided the amp has available clean power way in excess of what you might think you need - that is, lots of headroom. It's significant that most amps are no longer rated for continuous power but for burst power, i.e. power that can be maintained for only a few tens of milliseconds. In fact, it seems from tests I've read that most SMPS powered amps will shut themselves down if you try to get their maximum rated power for several seconds continuously. If you want "oomph", which I take to mean the clean power to deal with attack , then stick with iron or choose a class D/SMPS amp with several times the power rating of a conventional amp that would do the job. That's where multiple kilowatts of Powersoft amp comes in handy. On the other hand, there's no reason at all why a SMPS couldn't be engineered for the purpose if some of the size/weight advantages were to be sacrificed. I'm not a design engineer so this is more gut feeling than anything else, although I was a maintenance tech in broadcasting for 20 years in a previous life so it's not a totally uninformed gut feeling.