Re: Simplest Lip-sync equipment?
 

Well, yes and no. If you were playing a 2-piano 4-hand duet, ideally you'd use two identical pianos. So the second piano would need to be identical to the "player piano" (except that it would not need the reproducing mechanism).

Re: Simplest Lip-sync equipment?
 

If you would record two artist playing piano, there would not be so much question.
So just consider you are recording 2 artist playing piano.
Just use high quality loudspeaker that reproduce as much as possible the first player and record it as if the sound would come from a real piano while you are also recording the 2nd player.
if in the final recording, the first piano doe not sound too good, you can superimpose the first recoding to add more presence.

Re: Simplest Lip-sync equipment?
 

Here's a link to Yamaha's player piano. Excerpt from it:
"As with other MIDI instruments, one potential benefit of the readily-edited MIDI data output by a Disklavier is in the professional recording domain, where a recorded performance could be edited, allowing the correction of minor errors after a take."
Disklavier - Wikipedia, the free encyclopedia

Re: Simplest Lip-sync equipment?
 

Just place a small speaker on a boom arm as close out of frame as you would with a shotgun mic.

You've driven home the point about the talent not wearing ear buds are headphones.

Anything short of the above at this point seems you're not asking for a solution but asking for sympathy.

Re: Simplest Lip-sync equipment?
 

Six days ago I suggested dropping the thread, and I haven't posted anything for the past five days, so obviously I am not asking for anything at this point. Unfortunately you've chosen to revive the thread.