A UPS will do absolutely nothing to help this and he already has a Panamax power protector.
I disagree strongly. Those type of units if they malfunction could easily add noise to the AC. The fact this is ALL channels makes me suspicious of that Panamax.
I really don't like those sort of units. UPS units coupled with whole house surge protection give by far the best and safest protection. With his very large investment, he does need top of the line protection. It works the best when you have separates, as power amps should not be connected to any type of protective device, other than whole house surge protection. Power amps with there highly variable power draw which is large at times, are not good candidates for any complex protective devices.
A UPS is the way to go, as they almost instantaneously totally isolate protected devices form the AC supply. They let you know when the AC is out of spec. They saved me thousands a few years back and also my neighbors, when a regulator in the neighborhood failed.
Absolutely high end systems and really most systems need protection by whole house surge protection and UPS to vulnerable units, which means everything except power amps. This is another strike against receivers.
In my HT room, the three racks have a UPS of appropriate power at the bottom of the rack. There are power strips at the back of the racks, that all protected equipment are connected to. This includes the TV, supplied by the UPS in the first AV rack. The router, Ethernet patch bay and hubs are also protected. The power amp case has two circuits directly connected to the panel. The amps are stated from 24 volt relays.
This is a really good installation design and extremely stable. I have used this architecture for 17 years now. It is time tested and passes with flying colors. It is not overkill and what is absolutely required for a professionally designed high investment installation.