I had a JVM410 for 4 years and gigged it quite regularly. Cleans are great, but the real clean (Clean channel green) has a lot less volume compared to the other channels. We measured it, it is a 100 watts, but still lacking compared to other channels. Dirty sounds are ok, on OD channels orange and red modes are useless if the gain is above 11-12 o'clock. Instant squeal. The Fx loop has a problem. It has around 3-5db volume loss when used in series mode. Even Santiago said it's an issue, and you need to compensate with dialing in some dry signal with the loop mix knob. If you are using a noisegate like a Decimator Prorack G, it's a PITA due Od channels will still squeal. The amp is quite bright especially turned up, it needs a greenback type cab IMO. It's midi capable, but you can only send PC messages to it, and cannot control individual sections (Channel, mode, reverb, loop, master) just saved sets of settings.
I played an EVH 5153 with a matching cab once, and the JVM was sold in a week. That amp just kills. Great cleans, awesome Marshall type sound on channel 2, fluid leads with channel 3 . 3 Masters, 3 presence and a loop only comparable to an OD100 loop. I set the bias to 130 and changed a tube on channel 3 to a 12DW7 and the compression is gone, now it's like Channel 2 with more gain. Sounds great on low volume too. The EVH 5153 cab is wonderful too. Probably the best cab I ever played (considering almost all Marshall, Mesa Boogie and Bogner cabs). It sounds great with any of my amps.