frequency range for instrument vs speaker

Lloyde, I agree with you that there are definitely a lot of information below 40Hz in most music even though the natural fundamental of instruments used do not go below that.
Technically classical music probably have more instruments that can be played with fundamentals down below 40Hz.
So let say, in pop music without synthetizer, the extra information below 40Hz, are those something that is naturally supposed to be there or are there mostly created artificially from EQ or or sound mixer board (in live performance)?

Any full size piano (upright included) would be able to play 28Hz since they all go down to A0. Bosendorfer imperial grand actually has 97 keys instead of the usual 88 keys so officially it will play down to C0 which is about 16Hz. Not that there is that many piano piece that requires anything below A0 except few that Bosendorfer commissioned. I think Bosendorfer believes that these lower keys, even if they are not used directly, will give sympathetic vibration so the piano will sound fuller and more powerful, I think.

Drew, thanks for your information. I certainly don't disagree that giving bass extension can help to improve midbass performance as well. However, I don't think that it would answer my question regarding playing music that contains fundamentals that are only 50Hz or above as to what kind of sound, information or contents those recording contains that are below 50Hz? I am not trying to pick on recording studio, sound engineer regarding equalization or anything like that but actually try to understand more about what I hear.

Johnnyb, thanks for your information. That's exactly the kind of info I am looking for. Any idea how low those bigger kick drum can go down to? I also have not been able to find much information about the big bass drum that are used in some classical music such as Verdi's Requiem, Stravinsky's Firebird as far as their frequency is concerned.

Hmmm.. I looked into undertone a bit as well as phantom tone etc.
http://en.wikipedia.org/wiki/Undertone_series

It seems that undertone is rather rare unlike overtone which is all over the place. If the article is correct, only wind and string instrument can create undertone.

Piano can create tone lower than fundamental of notes struck through sympathetic vibration of lower strings.

Ecruz, I agree with you. I had similar experience with sub and perceiveds something similar so there is definitely something going on in the sub 40Hz area.