Dearth of auto-power on/off and auto-switching amps/receivers has been annoying me a long time and I'm sick of hearing sclerotic A/V people talk about how it's unnecessary or impossible -- it is a huge part of just immediately getting to the music/content without fussing with knobs, buying extra overpriced stuff & cluttering up space with ugly A/V remotes and equipment.
I can't believe manufacturers aren't building this into more amps/receivers given 1) how feasible it already is to stream from phones/computers/smart devices etc. and 2) the way people now just want to integrate content from difft sources in the flow of their daily life.
One of the only amps I've seen that does this is the Onkyo LS3100, surprisingly it is discontinued but still on the market, and I'm sure the auto-sensing feature is responsible partly for its viability. I have one connected to both an AppleTV and my regular TV and it seamlessly powers on, switches sources, & goes into standby when I'm watching TV, watching the AppleTV, or listening to music streamed from a phone or computer over AirPlay to the AppleTV.
I can't stress what a difference it makes. When we're in the kitchen making dinner I can just use my phone to stream radio (via Airplay to the AppleTV), when I sit down at the computer I stream music, and if we watch something on the TV or AppleTV we automatically get audio through the LS3100 amp and it happens nearly seamlessly, no searching for remotes, turning things on, remembering settings. I qualify this a little bc there is still a brief delay of about 5-10 seconds when streaming over AirPlay to the AppleTV before everything wakes & syncs, but I find this pretty minor and assume these delays will dwindle w/ every iteration of these devices & protocols. The LS3100 subwoofer is also wireless which makes the system that much more unencumbered.
My other complaint is that the LS3100 is slightly underpowered, so I would love to find another integrated amp w/ a bit more wattage but I just refuse to give up the auto-sensing functionality.
Please keep posting if you find other amps that do this.