@jon_5912, I think you mean 64 Watts for 102 dB. And one would need 256 Watts for 108dB. Now one would not ordinarily play Thiel’s that loud, but should it happen you wouldn’t have to worry. Ultimate volume levels are a Thiel weakness. For me the Thiel virtues outweighs the compromises, and the speakers that can play that loud are too compromised elsewhere for me. Though not the last word in accuracy, I’ve used a phone app to track my listening volumes in my roughly >3800’cubed room for a few weeks. The average sound pressure was about 85 dB, but there were peaks a few times each day of well over 100 dB.
It’s not the ultimate power of the Krell’s that impresses me the most, but rather the ease in which it handles low impedance loads. There’s nary a strain, and it’s reflected in the sound. BTW, with my >4 Ohm Thiel’s I use a less powerful amp that’s not a Krell.