[Musicians] Piano in mixing board question for contra dances

Hi All, Something totally different... ... for those of you with pianos in your band. Do you find that plugging in your piano stereo (using both the L&R jacks into the board) impacts the sound going into the hall vs just using the mono (one jack) option? My piano model (Yamaha P115) hasn't sounded super awesome in our main hall but Pete Sutherland's Yamaha P105 sounded great when he came a few years ago. I'm now wondering if it might have been that he was inputting two channels into the mixing board whereas I have only being doing one..... ... thoughts? Or other suggestions on how to improve the sound? With thanks! Emily in Ottawa