Suggestions about nice Computer based transport/player

Hi
I have resigned from car audio and recently put together a decent Home stereo system. The only missing item is a source which I want to be computer based. Even though I want best possible sound but I also want ease of operating it using a phone or tablet. This thing will sit with rest of my system and will use USB out to Metrum DAC. Not looking for NAS or server kind of stuff.

So I would be looking to DIY a computer based trasnport with cd drive to rip my 1200-1500 CDs to SSD drive. I am not in a mood to spend too much on Innuos or Antiobodes based systems and I guess I can do a decent job with right components. I have already bought a Matrix Audio X USB card. I have also shortlisted Streacom alpha FC10od and HDPlex cases and HDPlex 200W LPS. But I have no idea which mobo, cpu should I go for. Total budget is $1200-1500.

Currently I have attached a old laptop with 300GB music to Metrum Adagio via Anticables 3.1 which I thought was quite an upgrade to stock USB cable, EAR 868L, Threshold SA/1 monoblocks, Focal Electra1038 BE and decent cables. Sound output is quite good honestly I guess with good CAT things will be even better.