[Slimbo]

We do (or did) have modular options. The Chromecast audio was almost perfect in this regard, a $25 dongle that could be added to any amp/speaker setup and do all the 'smart' you needed including multiroom. Google have pulled it though, presumably the margins aren't there for $25 dongles vs $150 integrated devices. Given nobody else has stepped in to fill the void left by chromecast audio, I'm guessing it just isn't commercially viable.

[mrobins]

Same with Airport Express which had a killer side-feature of a AirPlay-able line out. When mine goes I’ll be searching eBay for another one.