What are the best loudspeakers under $4000 to re-create lifelike piano

philjolet, that $4000 will also buy you a pair of Eminent Technology LFT-8b's and a pair of subs. I would at least check out the ET's before pulling the trigger. Read Robert E. Greene's review in TAS a couple of years back.

Also, the latest Absolute Sound says that Manepan is offering a 60 day in home trial on their 0.7 mode (in their 2017 top picks supplement) ...but I don't see this on the Magnepan website.  I listened to the 0.7s recently through a Parasound integrated and they sounded very clear and spacious from the lower mids up....but a sub would definitely be required

If you’re willing to bust the budget (big time) and live with a limited selection of recordings, there’s a "right answer" here:

The diskclavier system, which retrofits to a piano. Effectively, you get a disc-driven player piano. I think the system is owned by Yamaha, but it can be retrofitted to other brands. New Disklavier uprights from Yamaha IIRC start at about $11k or so. A small Grand is closer to $20k. My local piano store has a small, second-hand Kawai Grand with Disklavier available for $12k. That set-up, with or without a disc inserted, sounds (and plays) great.

Im pretty confident that a used Disklavier acoustic piano will get the best recorded piano sound you can find at +/- $10k.

If you really want to stick to traditional-ish loudspeakers, I’d go for powered ATCs. I’ve used them with a Roland digital piano and the sound is pretty damn convincing to my ear. To be clear, I typically use Yamaha powered monitors (very good sounding, themselves) for this purpose (cost considerations), but - several years back - I had a pair in my studio to audition because a friend was selling them. They’re really good, IMO.

BTW, I also play back recordings that I’ve made of the Roland into my DAW (using a variety of virtual pianos, but not the Roland’s internal sound engine) via an Ohm 100/Rhythmik Subwoofer system that is digitally crossed and corrrected with Audyssey. It’s quite a different sound than I get from ATC monitors straight out of the Roland, but it’s very satisfying in its own right.

One more note, plus caveat.

One poster was dismissive of digital piano recordings. I disagree. The odds of getting a good result are vastly higher with digital recording, IMO. My home studio isn’t set up for an acoustic piano, but I’ve been to commercial recording sessions where we made an analog recoding of an acoustic piano. It’s not easy to get it "right" and there can be a ton of debate as to what "right" actually is.

I routinely get excellent results recording a piano in my home studio, using piano-teq modeled pianos, and Ivory or NI sampled pianos. The very best SQ piano recordings may be analog sessions with a great instrument, a great space, and a recording team vastly more skilled than I am, but - on average - digital recordings are preferable to me.

Caveat: My sensitivities to flaws in a recording aren’t necessarily the same as anyone else’s. A squeak from a bench can (and has) ruin an otherwise beautifully recorded passage.

@martykl - not sure if you were referring to my earlier post about the Nord not sounding like a real piano (or a Rhodes for that matter). Just to be clear if you were referring to my post, I wasn't talking about the recording process, digital v analog, but the instrument itself. Yet, at least live, I've heard some electronic keyboards that do a pretty impressive job of emulating an acoustic piano. 
On the history of pianos, those old "reproducing pianos" (which were more sophisticated than a plain 'ole player piano) could let you hear Gershwin playing his compositions. Crazy. Apparently, some (or all?) have been ported over to the Disclavier.