Tony - I am not surprised you heard improvements with your wood floor. That is consistent with my long-term experience with hi fi and live sound. One problem with carpet is its frequency-variability; different frequency bands are absorbed or not in non-linear ways. For the record, I have gotten best carpet results, including at Thiel's Music Room in Lexington, with wool carpet over commercial hair-pad underlayment. That's when carpet is necessary, such as when covering concrete where wood is not an option. In live performance, ensembles and/or the piano is often placed on carpet to quiet the reflections for the player(s). It does that, but not linearly with frequency; plus the effect in the audience is often an unpleasant harmonic unpredictability.
In my personal experience, it doesn't get any better than a wood floor. The record-making process tends to assume a wood floor for playback, as does the underlying theoretical physics. Jim's designs all employ a 2dB shelf below 200Hz in the anechoic response to account for the presence of a floor - converting the full-sphere anechoic response to the half-sphere in-room response. Some brands ignore this design element. Some users call Jim's designs "lean", etc. That "leanness" is exacerbated by carpet, sucking out some areas of response.
Congratulations on your wood floor. Music heals some aches and pains.
