@dogearedaudio You are correct that Sanders is speaking about ESL for the most part. I listened to your attached file. Very interesting. I would suggest you could start at the 25 min mark as he doesn't really get into the meat of the subject before that. Incredibly knowledgeable guy. Kind of funny how many of the amps his own company produces are in the 50 - 100 watt range when 5 watts is sufficient for 95% of speakers and 99% of listening rooms (I think I got that right). Anyway, a good listen for sure. I liked his comment that we should all start by choosing our speakers first and then work backwards to the right amp. Maybe that's why I liked the Sanders paper as I am running very large panel speakers. Cheers.