While I have certainly not tried them all, I have owned and/or listened to a few/several. Actually liked the initial sound, but over time I grew tired of them and was disappointed the more I listened to them. I think, or at least like to think that there is a great future with them. However, I am a bit suspicious of the wide pricing range and the super megabuck versions in terms of improvement over many of the more moderately priced ones.
So in the end, I am not currently/presently sold on their sound/performance and found them lacking for my expectations in too many areas.
Whether right or wrong, I have found that with virtually all components I have tried (quite a few), that the bigger and better the power supply side, the better the sound. So far, I have found this to be true with Class A and tubed amplifiers as well.
My suggestion for those considering the Class D amps is that very extensive (lots of time) listening be performed prior to purchasing, preferably in one's own system. I think they deliver a generally appealing sound initially, but I myself found the ones I have auditioned and owned lacking in the longer run. Perhaps my sound goal differs from others, but for my tastes this was/is my experience.
