I guess you should have looked further- the Niles distributed audio amp model numbers indicate the number of inputs (8), Zones (6, stereo) and power/channel (30 minimum).If 30W/channel isn't enough, each zone has a pair of RCA jacks for feeding power amplifiers.
Also, where did you see that this is a 70V amplifier? It's not. The specs show power into 4 and 8 Ohms. The SI-245 amplifiers are stereo, outputting 45W/channel (assuming the SF was a typo and I have yet to find an SF-245).
You're assuming, again. 70V is used wherever it's needed.
We get it. You like your system and think just about everything else is crap. It's not for you to decide, it's for the people who have something, to decide for themselves.
These were used in houses, as well as commercial spaces. You may not be familiar with the types of homes, though- they tended to be in the 10,000 ft² and larger variety, or when a dealer had a client who wanted what these could do for them and nobody ever said these systems would provide the ultimate in sound quality. When someone who has a lot of money wants something that will provide music throughout a house, this was a decent way to accomplish that. One system that I worked on (after it had been installed) contained 14 stereo Bryston power amps for the audio distribution and IIRC, it had at least 6 Radio Shack ground loop isolators but that system was Crestron, not Niles. In another house that covered roughly 19,000 ft², the system included 40 channels of distributed audio. I also installed two Niles ZR-4630 amplifiers in a Harley-Davidson dealership in Kenosha, WI- again, it's for distributed audio, not the ultimate listening experience.
If you look at the rear panel in the photo, you'll see that it only has composite video connections and that places it in the late-'90s/early-2000s time for introduction and it wasn't sold by the typical stereo store, setup was far more complex than most of them wanted to deal with.
Niles ZR-8630AV Manual Online: Specifications. ZR-8630AV Audio/Video MultiZone Receiver AMPLIFIER SECTION Continuous Average Power Output (FTC) All Channels: 30W per channel min. RMS at 8 ohms, any two channels driven from 20Hz to 20kHz with no more than .05% THD. 37W per channel min.
www.manualslib.com