dac and streamer or seperates

No long winded answer here. Separates 100%
im not going to recommend anything nor will I push my system on you like most do. I will say I was where you were a year ago and switched to separates. Huge improvement

I would recommend separates but in this price range I would go with one unit.  Check out Lumin as they are a great value and provide versatility as well as the ability to isolate features later on should you want to upgrade.  Initially I used my T3 as a dac and streamer then upgraded my dac and used it to stream. Also Lumin is great choice if you choose to use Roon. 

Here’s a different approach - get BOTH a DAC/streamer combo and then find. Streamer separate. Keep your eyes out for a Modwright-modded Cambridge CXN V2 on the used market. This unit has a streamer and DAC built in, Dan Wright overhauls the analog stage with a tubes and quality lundahl transformers while installing robust linear power supplies for each the analog and digital sections. It can be found from time to time for $2K or so on the used market. You can use the built in streamer for a while until you settle on a better one. On its own it will best most other separates in the $7-10K range. You can then take the time to find the best streamer for your budget, or save more for an even better one. Used Aurender units will get you really far. Lumin is in pretty good for the money as well. 

Separates period. 

I'm in the minority, but my preference was a single box DAC/streamer.  Hardcore audiophiles usually prefer separates all around, but my thinking is the one box units have a better matched streamer, DAC and power supply.  I would also think better bang-for-the-buck as it's one chassis and no extra cable to buy.  I don't do upgrades frequently, but I can upgrade the streamer or DAC at a later date with digital inputs/outputs on the chassis.  I chose the Cary DMS-700 which would fall in your price range if bought used or the DMS-650 new would be in your range.