The KSA-80 is 80 watts of Class A, this guy draws full power at all times from the wall, and makes lots of heat, the 100s contains the Sustained Plateau Biasing, thus the (S) designation. Not drawing full power until it thinks it needs it. The power supply in the 80 is more substantial, the 100 was completely different technology, not better, just different.
E-mail if you have any questions about the 80. I'm not familiar with the 100-s as I have never owned one.
E-mail if you have any questions about the 80. I'm not familiar with the 100-s as I have never owned one.