I am a long-term CLS and CLX owner and have always driven them with tubes. Purchased CLSI's and drove them with an ARC D115mkII (100 watts) in the 80's and subsequently upgraded the speakers all the way through CLSIIz's (and had Entec subs). About 2015-16, I purchased an ARC REF110 (110 watts). Both of these drove the CLSs well and I don't think there is a substantial difference between 80 and 110 watts.
In 2017, I upgraded to CLXs and a REF150SE at the same time. More power (150 watts), but I was in a smaller room at that point, so did not really need it, although I did appreciate the increase in resolution, etc. I did add a BF 210 sub, for bass extension, not for increased output.
I think you will be fine with 80 watts, except if you want to listen concert level loud. My bigger question is whether Summit X's are better or worse than CLSs with a depth sub (and the custom crossover file). This is partially dependent on the status of your CLS panels.
In 2017, I upgraded to CLXs and a REF150SE at the same time. More power (150 watts), but I was in a smaller room at that point, so did not really need it, although I did appreciate the increase in resolution, etc. I did add a BF 210 sub, for bass extension, not for increased output.
I think you will be fine with 80 watts, except if you want to listen concert level loud. My bigger question is whether Summit X's are better or worse than CLSs with a depth sub (and the custom crossover file). This is partially dependent on the status of your CLS panels.