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

Streamers are computers. So is your iPad and phone. Using a computer that's designed for streaming can be better than a laptop or desktop but there's no hard and fast rule. I'm using a NUC running ROCK if I'm going through Roon. I can also connect my speakers to my network and stream direct to them. I use a tablet as the controller. 

Streamers are indeed computers, but run relatively few processes which means less noise generated. Add better rendering capabilities vs most computers, servers/streamers, wins on two counts. Streaming dacs are also nice, foregoes external rendering which can be advantage.

really; there are three different circumstances regarding this question; "it depends".....

1--at the entry level it’s a horse apiece.....computers are servers. servers are computers. maybe a dedicated server has slightly less noise, and maybe a better power cord than a sever; but likely your network bandwidth, network switch, ethernet and usb cables will have a greater effect than other choices at this level.

2--mid level dedicated servers will outperform regular computers and laptops since they eliminate much of the peripheral noisy processing duties of the normal computers. there is a clear difference to go dedicated.

3--price no object server levels they far outperform any computer or laptop. but you are talking $20k to $100k for a music server. i own a $76k music server and it is awesome sounding and significantly outperforms my previous $30k+ music server. once i heard the difference i could not 'unhear' it. and took the plunge.

No surprise everyone has a different generalized answer.

The correct answer is still the devil is in the details so it depends. Cost or product category alone assure nothing.

I will say from personal experience that $3k spent wisely on a digital front end can get one very very far these days. Maybe less if your amplification is already in order. After that you are splitting hairs most likely. But only if spent wisely. That means sticking to the latest and greatest technologies from proven vendors because the technology has come a long way in recent years and still moving.

I went from node to a dedicated NUC computer to stream via roon.  I then tried an Allo USBridge sig streamer.  While sound seems to be slightly better, then more enjoyable improvement is seamless streaming.  Never does the streamer fail to deliver the requested digital bits.