Best Audiophile desktop for under $2500?

I will be installing a Matrix Audio USB card for the DAC, not sure how much of a difference that makes compared to a USB/fiber optic scenario. I do a lot of 7.1 HMDI audio/video/movies also. There is about 14 TB of music. Thats another reason the DELL worked out, because of all the bays to add HD's. Has to be Windows based for when I do work. I mainly use JRiver. The reason I mentioned ROON was because I was thinking of using it also. But the main software is JRiver. 

Wondering if I can use my current DELL as a server somehow and use another computer in the system. Is there a way to make that scenario work?

Cant do a MAC. Need Windows for work. I also sometimes use the PC to DJ also... like Serato, Rekordbox, & VirtualDJ. These programs need some good specs to run smooth.. But that's not my biggest concern.. would be nice to use it for that also though. The Matrix Audio Element H USB 3.0 Interface card isolates the USB signal and uses a separate power supply. This needs a PCIe x1 Gen2 Interface. It makes a significate difference.  So if there is some kind of fanless.. or quiet enough fan PC or Mini PC.. that might work.. but needs to handle a decent workload. I still like the idea of using my DELL as a server considering its one less expense. The OPPO outputs HDMI when playing movies or multichannel audio. But when playing hi res audio like 768khz, then I would need to switch to USB and use the PC HDMI. So the PC would need at least 2 HDMI outs. One to the OPPO and the other to my projector.