Though the passband of the piano soundboard/strings may be out of the range of the sub. However marginally, since they can both play many of the same frequencies, that, to me, is only one consideration. You may not get any string or panel excitation from harmonic coupling, there is still a vibration that is more mechanical in nature. If a painting or mirror vibrates on a wall from the bass energy in a room, it can be the mass of the painting was excited or sympathetic vibrations travelling through the higher mass of the wall. This is the primary concern I would have with the piano. As having been raised around pianos my entire life, I can assure there are many variables that can affect their performance and mechanical durability. I am only saying, in point, that I would proceed with caution. Car analogy: keep in mind all the loose nuts and bolts on your car were undone from vibration. :hsd: Cheers, mate!A very good point! My hope is that the frequency response of the sound board is above that of the sub. This seems possible, especially in light if the fact that the piano is a 6 footer. But as you suggested, only way to know is to try it out. As for tuning, I have to tune it every 6 months (sometimes less) for the studio purposes anyway, so that's no big deal. And I can't think of any possible way of permanently damaging the piano with audio.
This is the reason why I drive a Toyota!FLAudioGuy said:I am only saying, in point, that I would proceed with caution. Car analogy: keep in mind all the loose nuts and bolts on your car were undone from vibration.