I think this post above captures the source of my disconnect from the "streamer" paradigm very well. I probably should have noted that I am a passionate DIYer, not an "audiophile" (fool?) with an unlimited budget that is looking for the best components available that provide the best performance. I build my own loudspeakers and enjoy working on niche and esoteric types that provide some interesting benefits as well as many technical challenges. Early on I wanted to build a "wireless DSP based loudspeaker". To do that I needed to come up with some functionality both to get the audio to the loudspeaker wirelessly, and to perform all the DSP functions required for the crossover. This lead me to brew my own solutions, and these crystallized a few years ago into the system I use today that is built using Gstreamer. Since it runs in software on small and inexpensive computers, I naturally use one of these as the source for my playback system. By connecting a USB pro audio interface I am able to bring audio into the computer from analog sources, and can access and play digital sources and streams using the computer itself. Then the audio is sent over my WiFi system to various loudspeakers I have built or bought and that exist within my home. At one time I had six or seven such projects connected to the system. Playback is tightly synchronized to within a few tens of microseconds.
When I started this thread it was from the point of someone who already had all of the functionality of a streamer component (and more). But I totally failed to see the perspective of the audiophile who does not actually build anything themselves, and who would just like to enjoy some streaming audio with minimal setup and with high playback quality. So apologies to those who fall into this category - you are stuck with whatever commercial gear is available.
At the same time it is interesting to see the spectrum of replies to this thread from people who have taken some steps towards a DIY solution, even if it is just installing and running some programs on an old laptop or computer. Audio for me is a hobby not only to listen to music but also to create things related to that, and to enjoy the challenges and learning about the technology behind many aspects of audio reproduction. But everyone is different and interacts with audio in a different way, and what makes sense to one person may make no sense to the next one. If a streamer makes sense to you, by all means enjoy it!