Streamer/DAC - Where is the value?

@anotherbob you inspired me to explore the Tidal vs Qobuz question.

My brief listening notes with a couple of Stan Getz tracks, Girl from Ipanema and Desafinado:

Qobuz: slightly higher volume needs equalizing with Tidal. Sound image seems more stable, fixed. Clear left right and center images. More upper mids and bass resolution but doesn’t seem to go as deep. Tried briefly to use dB app to measure differences but unreliable. There seems to be more air and transparency around the bass, more reverb.

Tidal: image seems denser, more depth and bloom. Not as clear and transparent, more bass bloom and depth. It seems to go deeper but couldn’t validate that. It just sounded quite different from Qobuz. If you like lemon gelati, fresh and open you’ll go for Qobuz, if you like rum and raisin ice cream you’ll be a Tidal fan.

I still can’t make up my mind.

Your weak link is not only the Cambridge, it’s also your Mcintosh IMO. If you’re looking for value it’s not in Mcintosh. I went to Simaudio from Mcintosh and find it’s way better dollar for dollar especially in the used market. Not saying Simaudio is the best but I’ve heard tons of gear that blows Mcintosh away at way lower price points. In terms of DACs I’d say your suggestion of Auralic G2.1 and use as a preamplifier then buy a decent amplifier like a Pass Labs, Bryston or whatever you like. I’m currently using U1 mini with Denafrips Venus. Sonus Faber Minima Amator 2 and Simaudio 340 i.

While I definitely understand the wisdom of keeping the two separate, I purchased a bundle from Cary Audio. Their DMS650 is a DAC/Streamer priced at $4800. They are always running sales and you could probably get 15% off right now  

Unfortunately my only comparison is a Bluesound Node although at a dealer I did quite a bit of listening on a Cambridge unit. The Cary unit had an extremely profound impact on the sound of my system. This was not a night and day, this was a Quantum leap. Not only did the quality and clarity improve dramatically, but the power and impact of the sound was stunning. Maybe that can be said of any DAC and Streamer at that price. Steve Huff said this unit punches above its weight and is an easy recommendation for anyone spending up to 6k coincidentally. They also have B stock on their website which is discontinued models. They have a few DMS 550’s at $2995 right now, but those are exempt from the 30 day return policy. 
Based on my experience, the DAC is perhaps the most important component in a digital system. Prior to the Cary, I was on the verge of buying an MA352 and choosing a DAC later. But after hearing the Cary combo, my decision was made. The SQ, nuance and detail were far superior with the Cary combo. What attracted me was the realism and vocals. The drums actually sounded like drums. And I’m a lifelong drummer. The cymbals shimmer and decay naturally. On good to excellent recordings, this combo is stunning. The Cary sound is said to be natural but not fatiguing. I must concur. 
Happy hunting. 

Of the products the OP is considering, in the $4K-$6K range, volume control (preamp functions) may have a bigger impact on SQ than the DAC, and an even bigger impact than the streaming functions.  A couple of Chinese companies (Lumin and Matrix Audio) make a big deal of their hybrid (digital/analog) approaches to volume control. They offer interesting integrated streamer/DAC/preamps in the $4K-$6K range (or a bit higher).  If you're in the USA/Canada and want to stick to North American products (for the service/support), then consider PS Audio (Colorado); Exasound, Bryston, NAD (Canada); Mytek (USA/Poland). 

IMO, in the $4K-$6K range, with respect to streaming/DAC/preamp capabilities, you may not notice all that much difference in SQ (again, esp. w.r.t. the streaming).  Maybe focus more on features/functions and on the after-sale service/support.  With digital components, you'll almost certainly run into software/firmware issues. So it's a plus to have a company with a relatively big user base and a strong service/support presence in North America, the UK, or wherever you are.

This question gets debated quite often on this forum and others.  Seems to be 2 camps on streaming / DAC and which is more important.  Most fall into the dac having a bigger impact.  I don’t sit in either camp, I think it all matters, can make a difference, think synergy is key.  I’ve had a Node 2i, used it as a dac / streamer and as a stand alone streamer feeding Parasound P6 internal dac, have had a Lumin D2 with S/Booster used as an all in one and streamer only. Have a Krell Pre Illisions ii with a DAC, my HT Receiver / Anthem MRX1140 and a MHDT Pagoda balanced.  Also used Roon with a laptop in the mix, with the Node / Lumin / Pagoda.  Today I have a Aurilac G1 Aries streamer only feeding my Pagoda and I’ll switch over to the Krell DAC from time to time.
 

My learnings for what they are worth, bang for the buck, Node is a great little unit, Lumin was a clear step up in sound quality as an all in 1 unit.  I used both as streamers only, sound quality improved when I put a stand alone streamer into the mix.  My favorite combo of them all has been the G1 and Pagoda being run entirely balanced.  
 

My 2 channel is balanced all the way through the chain, the pagoda balanced steps up several levels when balanced inputs /outputs are used as does my Amp, Krell 300xd duo.  My experience with Roon was sound quality suffered slightly vs using Lumin / Node or Aurilac software directly.  That’s likely due to my system, set up as others love Roon - it does have a great interface, the best I’ve see.  I’ve also used a PC / Laptop as the streamer, fed the dac directly, my experience has been things have always sounded noticeably better with a streamer in the chain. 

Another huge factor is the software / interface the streamer you pick uses.  Node uses Bluos which on my opinion is the best of the bunch, has the most flexibility and staying power.  Lumin and Aurilac would be tied, might give a slight edge to Aurilac but negligible.  Some will overlook this aspect in a streamer, it will have a massive impact on your enjoyment and ease of use when you stream - listen to music, all 3 listed support their respective platforms, have invested in the ongoing development.  Bluos has the most $$ behind it and traction but Lumin and Auralic are more invested specifically in the Audiophile community.  
 

Age old question of All in 1 vs separate Streamer / DAC.  Comes down I think to personal preference.  If you aren’t a tweaker, you can get a great bang for the buck and synergy which is key from an all in 1.  Lumin makes outstanding products in the space - most are all in 1 units.  Others that also make fantastic all in 1 products that rival or beat separate set ups.  Many companies that make both, to no surprise design their streamer / dacs to perform best when paired together, synergy is key. If you want to swap gear out, hands down, separates is the way to go.
 

As others have recommended, you might look at the Mac - spend the money you would on a streamer / DAC - buy a highly regarded integrated with a built in DAC.  Try that, use your Cambridge unit as a streamer, play around with seeing which you prefer, the Cambridge DAC or the one in the integrated.  You can then sell the gear that isn’t the winner of the best sound to you contest, build out from their.  I’ve never heard many of the Integrated units talked up, some that get tons of praise along with being referenced as having outstanding DAC’s - Hegel 390 or 590, most think the 390 is the sweet spot.  You can get either used at your budget or slightly above, again, never heard either, but reviews are off the charts, if you search you’ll find some other Integrated units that sit in that same camp as having great internal DAC’s built in.  If one floated your boat, you can pair with a streamer down the road, then add a different DAC into the equation - DAC rolling instead of tube rolling.

You have gotten a bunch of great recommendations - I didn’t see a brand referenced in the thread that doesn’t make a quality product, really comes down to what you want, simplicity, ultimate synergy or flexibility, being able to tweak, swap out streamers / dac’s.  The last comment I’d make is if you are agnostic to all in 1 or separates, dollar to performance ratio along with synergy will be achieved by picking one of the top 5 streamer / dac brands and going with a flagship unit that is all in 1.  Used you can probably find those in or near your budget. 
 

Good Luck!