Streamer choices

Lumin D2

I disagree with the comments about 320 streaming. In my experience a budget streamer does not produce as "good" a sound as a "higher" streamer regardless of bitrate. I have for example a DCS Upsampler and  that seems to drag lower quality sound into somewhat acceptable. 
I would suggest looking at a higher level streamer second hand, they don't deteriorate with age.

Arthurd - before making any changes in equipment, procure yourself a Qobuz account and, providing your connection to the Internet is fast enough (most typically are now), you will now be able to stream true High-Resolution audio, instead of being limited to what Spotify allows in their so-called “premium” service.  Even my 62 year old ears can easily tell the difference.  You might find yourself happy with the streamer/DAC you have now, too.  If not, at least you will know you’ve got the best quality sound streaming to your system!

Agree on first leaving Spotify. I am on Tidal using Roon through Innuos and into DAC. My set up works well. 

Arthur, I assume you're using analog-out from your Node to the preamp. If yes, then you can certainly do better. Not to say the DAC in the Node family is bad (it isn't), but there are better DAC's. If you like the McIntosh house sound, perhaps their streamer is your best bet.

Just curious .. have you compared the sound quality of the digital-out connections from the Node to your preamp's on-board DAC? 

I have a Bluesound Node 2 which I used for a couple of years in my main system (now in my work system). Using either coax or optical out to a better DAC than the Node's on-board DAC elevated the sound quality significantly for me. Many others have reported the same. 

BTW, I have a Spotify Premium subscription. For me, it's great for casual listening and music discovery. I really enjoy it and find the sound quality acceptable for the way I use it, and that's with a cheap Chromecast Audio. The Node is a terrific streamer and is likely all you need for streaming Spotify Premium. 

I moved on to a Sonore microRendu for more critical listening. It sounds wonderful with my own library of WAV files and Qobuz and was a indeed an upgrade over the Node 2.

Many ways to skin this "cat". Best of luck with your search.