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!