I mean sure, it's a notch above Wal-mart Bluetooth speakers, but we're not talking real HiFi equipment here... In such a case, you wouldn't hear the difference between players anyway.
I'm a bit confused. What is it that's a notch above Bluetooth speakers? I don't have any Sonos speakers on my receiver. I said I have a Connect.
You got everyone confused, and mentioned very late in the thread how you got everything set up.
On top of it all, you were not clear about what you are trying to accomplish.
You want the best possible CD audio? Any Blu-ray/DVD player made in the past five years will do the trick.
The rest of your equipment won't make a difference.
So let me clarify things a bit:
Digital is straightforward, analog has more weaker points.
At any point in this chain of equipment, the signal - whether analog or digital! - will dragged to the the lowest common denominator by the quality (or lack thereof) of the cheapest component. The more gadgets you include in the chain between the CD and your ear, the bigger chances you have that one of these gadgets - in your case, the Sonos Connect - will be cheap enough to affect everything else downstream.
If you had a NAD amplifier/preamp setup with separate mono stages, connected to Nautilus speakers, and listened to CDs via analog, then the quality of the player could have made a difference.
But when you include streaming devices like Sonos to the equation, the rest is academic. You have "consumer stereo", not HiFi. Your concerns about CD player quality in such a use scenario are as relevant as winter tires on cars in Florida.
Read
sdifox's posts again, you already got good advice there.