Thanks very much, Will.
The pi3 route is enticing. BUT, have you and others pursued it for the novelty and cost/benefit factors, or does a pi3 coupled with the other IQ/CorePlayer/Audiophonics devices you list actually produce a higher quality audio than say store bought devices as are available from BlueSound (NAD) or Linn (i.e., is the pi3 route technically equal or even superior)? I'm reasonably computer literate and don't mind tinkering, but just buying a streamer from a reputable brand seems such an easy turnkey solution.
The iFi Nano looks pretty cool for use on the go, as you suggest! And I already have the OTG USB cable.
Amplifier: Magnum Audio A.100 Mono-block Amplifiers (2 @ 400W/8R); P.100 Pre-Amplifier; PS.100 Power Supply
Speakers: Celestion SL700s
CD: Linn Mimik