I ran my Grand Piano (not HOME) from an ARC VT100MkII and single wired (not biwired) Kimber 8TC. I thought the sound was good and much better than I could have expected due to my preamp and cd player at the time. Based on this experience I do not think it is necessary that the GP be bi-wired.
Even in hindsight, after bi-wiring Duntech speakers with Cardas neut ref and running Avalon speakers with single wire, I do not regret running the Grand Pianos with just single wire (though I am curious as to the possible difference with bi-wire).
To beat a dead horse, the GP can sound quite good without bi-wiring.