Acoustic instruments go a long way in the realm of realism when a system is firing on all cylinders. If the initial movement (of a key, valve, etc.) is captured, followed by the strike of it, followed by the burst and then bloom, and then the associated spread, decay and reverb, the whole soundstage develops to a degree that can make one momentarily forget they're listening to a recording. A piano is a great instrument that can do that.
One can faithfully replicate the passing of a heavily laden semi without all the shaking when a piano plumbs its depths. A microphone placed close to the soundboard can be all it takes to make you forget and just revel in it all.
If your system can already capture and recreate that kind of moment, then you're almost there.
All the best,
Nonoise