Help setting up Computer audio rig

Brief description, I have 2 separate systems that I listen to music on, one stand-alone 2 ch audio system and a computer system. I've found that I haven't touched the 2 channel system in over a year, because I'm always at my computer when I'm listening to music. Also, the house I live in is very open concept, so when I use my 2channel speaker setup, it bothers my wife who might be downstairs working or watching TV.

So basically, I'm looking to switch/sell off my 2 channel setup and upgrade my computer's sound.


My 2 channel system is as follows:
sources: Rega P3 turntable and Rega Planet CD player
Intergrated Amp: Rega Brio 3
headphone amp: Gilmore Lite
Speakers: Focal Chorus 807v Bookshelf
interconnects: Atlas equator MKII RCA cables and Atlas hyper speaker cables
Headphones: Denon D2000

Here is a photo of my 2 channel setup:



My computer setup:
source: FLAC audio files currently going out of 3.5mm jack with onboard sound
Speakers: audioengine B5a (not the plus version, so I dont have RCA input jacks)
Headphones: Grado SR60 powered out of headphone output on computer case

Here is a photo of my computer setup



I'm looking for suggestions for a DAC preferably one with a headphone output that will be similar quality to the Gilmore lite. I love my Denon's but I'm also thinking about getting a pair of HD650's, so the amp/dac doesnt have to be specific to powering the Denon's. I've seen adds for the yulong D100 and Matrix quattro, which look good, but I'm not sure if they're above/below the level of the gilmore lite?

Is it better to use a USB to send sound to a DAC or should I be looking at optical or spdif? Do I need a sound card for that?

Also looking for suggestions of speaker placement on my desk - would it help if I had small stands or foam blocks? should I toe them in?

Thanks in advance

Does an internal sound card provide equivalent audio quality to an external dac?