...best ones have all major components galvanically isolated with fiberoptic cables.
That was the most BS statement I've read in a while. Thanks.
The most important part of digital audio is not the transport, it is definitely the DAC. The proper DACs and build quality matter a great deal, if you have the equipment to support the jump you will get from that quality. So, your speakers and amplifier are FAR more important than the DAC. The DAC is far more important than the transport.
So, having CD quality or better audio on your PC. Or from the Internet, that is run over cheap cat-5 cable to your streaming devices will have ZERO impact on audio (or video) quality. What will matter is the device that converts it from digital to analog. Bluesound makes a very solid product for the money and strikes a reasonable balance between cost and quality. I'm not sure I would use a Shield for audio if I had a Bluesound product. It's just an added point of failure. I would just use the Bluesound interface.
But, if I already had a Shield, I would just hook it up to a quality AVR via HDMI and let the receiver do the DAC duties and call it done. On a quality AVR with good DACs in it, you aren't likely capable of noticing a difference in audio quality, all else being equal.