The amps with the jumpered inputs are the Plexis. The smaller top one is 50 watts, the one under it is 100 watts. Neither have master volumes, they're both insanely loud, although I put a post phase inverter master vol (PPIMV) on the 100 watt. But I leave it cranked now that I got an attenuator. The attenuator sounds better than the PPIMV. The JCM 800 is probably even louder than both the Plexis. It has a master vol though.
Yeah, if it's anything but a 2007, then don't worry about it. 2007 is the only year you need to be concerned about.