Which device makes for a better digital music source? Computer or streamer?

I personally think the decision on if you should have a dedicated streamer or computer is dependent on what you are looking to do. If you want no fuss and your main concern is just listening to music then by all means a dedicated streamer will make your life easy with little hassles. On the other hand if you like to tinker and tweek things, you may be happier with a computer.

In my instance I wanted to do extreme oversampling (DSD1024X) with HQP and also wanted to use convolution filters designed for my headphones. This isn't possible with a dedicated streamer. I have a Holo Audio May KTE DAC that has a VERY GOOD USB implementation with very low jitter so using a computer for streaming wasn't as much of a concern for me. I think this choice will be dependent on your USB quality of your DAC. In my case my DAC has Galvanic Isolation. You could always try streaming from a computer and see how it goes. Startup costs to do this will be very minimal.

I don't stream in my listening room.  Uncompressed flac or wav files are stored on a ssd in a small form factor i5 running Euphony Stylus OS. DAC is a Bifrost 2. I'd have to spend many thousands more in hopes for a marginal improvement with a dedicated server.  No desire at all. My configuration wouldn't be taken seriously here since my monetary investment in it isn't 30,000.00 or more.

I'd be surprised if anyone could tell the difference ... 

Using a Cambridge Audio CXN version 1.  Sound is as good or better than my NAD CD player.  I can connect my PC (HP laptop) to the CXN through a USB cable but I cannot tell the difference between that and streaming directly from the CXN.