Ah, didn't see those pics, thanks for that! However, I still don't think that's a
true rack based solution, but I do agree it's nicely done. Probably the best somebody may expect with the limited options there are.
If you do really like Chromecast Audio, take a look at the NAD
CI 980 and
CI 940. With one of each and six Chromecasts you would be done.
Then you could just as well buy a
Dayton Audio MA1260 and be done with it in one unit and half the price.
Sure you can. There is audio gear for every price point.
I agree that NAD is a very good brand and very likely the better compared to Dayton Audio. On the other hand, what the amp needs to do here is to amplify chromecasts (so wireless signal for compressed audio) for in-wall speakers. I doubt you'll hear a difference in this user case.
But in any other HiFi use case, with some serious speakers being used, I would agree whole heartedly to go for the NAD.