Geoffkait…if you read my post you should be able to see I DO know something about useless tweaks.
There are tiny "transducers" people use that appear to be metal JuJuBees that are also laughable, and misuse the term "transducer," so beware of those also...My upright piano is against the back wall and it would take a VERY high level of sound to excite it. I’m not about to haul it out to check if it’s making a difference, but it does if you play it while my stereo is on…stop that…just stop...I’ve been a professional musician and audio geek for over 5 decades, and currently get paid to mix live concert sound for astonishingly accomplished musicians…been doing that for a couple of decades. This doesn’t make me more qualified to comment on stuff, but at least I can claim I’m a Professional something or other. I "tune" my listening room with its sloping ceiling that goes from around 8 to 15 feet or so, my furniture, carpet, books, CDs, myself, and jo mama.