Going back to basics

After a few years playing the A/V game I am going back to a pure audio system. My fantasy was I would just setup the A/V processor for 2 channel pure direct and use my sub for good quality Stereo. Unfortunately the processor wants to play the sub as just LFE and honestly it all just does not sound like my old preamp and mono blocks. 
The good side here is I a flush with speakers: 
2 ATC SCM 19
2 ATC SCM 11
1 ATC C3 center
1 ATC C1 Sub.
Currently play my digital FLAC files from NAS through my Transporter. 
I want a preamp DAC streamer that can play my FLAC and support Tidal and AirPlay (wife loves her Apple Music) I would like it to support Sub outputs but could go Y connector if needed. I would also consider new AMP/s  but honestly my Yamaha MX-5000 using Biamp config is not to bad. 

If if I flip it all I would Keep the ATC 19s and sub and sell the Yamaha CX-A5000/MX-A5000 and the balance of the ATC speakers to offset cost of new items. 

would like to keep the cost down around 5-7k
@mtj - I have also dome something similar for my own A/V system.

I purchased a Bluesound Powernode 2 which works for me..

I have an Apple TV + a TV streaming box with PVR capability.
- Both these boxes feed into the Smart TV via HDMI cables.
- I take an optical feed from the TV OUT into the PowerNode2
- I have a sub connected via the Sub-out on the Power Node 2
- The speakers are nicely driven by the 50 watt/channel amp inside the PowerNode2
- I have a pair of Tannoy Fusion 4 floor standing speaker

There is an analogue input on the PowerNode2 but that is one of those dual-use inputs that doubles as an optical input whidh I use for the optical link from the TV.

Not strictly "surround" but I am continually surprised by sounds that appear to come from the side and rear and the sub provides all of the LFE’s for those earth shattering moments.

The Node 2, has all the same inputs/outputs/capabilities, just witout the power amps,  so you could hook that up to your existing amp to drive the speakers

My other speakers are now deployed as a second, less used, A/V system in the basement.

Hope that helps - Steve

Hehehe .....   and I thought going back to basics meant a good pair of speakers, stereo intergrated amp and turntable. You say “tomato”, I say “potato”....
I also use a 2-channel (or 2.1) system for video. I think your approach, selling the center and surround speakers and processor, would be a good way to go. I would keep the amp for now as you are satisfied with it. Can always change that out if desired. 

The Node2i mentioned by williewonka certainly has the features you are looking for and with your budget you could use it with better DAC. I believe there are other preamp/DAC/streamers that could be considered. That option I will have to leave to others, as I will be in the market, however haven't as of yet explored the market, outside of this forum.