Well, you need a DAC of some sort in order to convert digital to analog. Whether or not the hardware that your DAC is part of also contains a streamer or has volume control or other functionality is a question you'll have to answer for yourself.
You don't need an expensive DAC (or streamer) to enjoy music, but you will have more options for higher-quality sound as your budget increases. Particularly given your choice of KEF Ref 5 and Pass Labs Int-250, you wouldn't want your other equipment to be less than up to the task.
The benefit of a network streamer is of course the convenience of listening to digital music either from your local library or one of the streaming services. Generally speaking, a network streamer does make the the music listening experience more enjoyable than connecting a regular computer.
You don't need an expensive DAC (or streamer) to enjoy music, but you will have more options for higher-quality sound as your budget increases. Particularly given your choice of KEF Ref 5 and Pass Labs Int-250, you wouldn't want your other equipment to be less than up to the task.
The benefit of a network streamer is of course the convenience of listening to digital music either from your local library or one of the streaming services. Generally speaking, a network streamer does make the the music listening experience more enjoyable than connecting a regular computer.