Best digital format (non streaming)

+1@ @arcticdeth. With the caveat that it’d be a cd transport and separate DAC.
My McIntosh MCT also accepts large capacity usb thumb drives. Helps me play my DSD files that don’t play natively through my Bluesound node. 

I noted down the referenced sites for hi res downloads. I will visit and check out what they have (and cost). Thanks for posting.

I have compared uncompressed FLAC to the WAV file and I can't hear the difference.

CD is best 

"CD is best": I have a decent (for my level/aspirations) receiver with a DAC. And my CD player has also a built in DAC.

As a first 'try', I would like to compare the CD player analog into receiver vs. CD player digital out (and conversion in the receiver), using (depending on which CD player I uses) digital coax, optical or HDMI (?) to feed into the receiver. 

Is that a practical test? 

I was utterly surprised when I listened to my ripped CD played from my laptop via 25 ft USB C cable via Schiit Modi 3 analog into the receiver, vs CD player into receiver (computer sounde a LOT better).