Please be gentle with me! 🙏

  Lots a accolades for the BS unit.  But I agree with @mahler123 the improvement potential is a crapshoot.

Demo an Auralic Vega 2.2 DAC/streamer…don’t buy it but at least get a reference point.

To answer your question, I feel going with something like a Bluesound Node N130 would offer better sound quality.  On the other hand, if he is Satisfied with his equipment situation and sound coming out of the speakers, I say all is good. Cross that SQ bridge when he gets to it.  It's his money and development into as my girlfriend calls me, "Stereo Lunatic".

Nobody knows what a streamer is or what it can do or can’t  do. What’s the difference between a server and a streamer? Isn’t a streamer a computer running some OS? Or do you call a computer running an OS a server? 

Can a streamer read ripped songs off a local disk? If so, that’s not a streamer is it?

Can a server running Roon access Qobuz/Tidal? Isn’t that a streamers function. If you are going to talk digital get your story straight. Or do what Aurender is starting to do to muck up the waters, they are now calling their boxes streaming server which is basically a computer running an OS, running some software, that can both read local music files and access Qobuz or tidal. Big deal, I’ve been doing this for over a dozen years, it’s nothing new.

I believe the bluesound will be an improvement. I started out with a bluesound node And I think it is an excellent product for the money. decent, sound quality, very reliable and easy to use. The app is simple and user-friendly. 
Good choice for your situation