Or you could have your hearing checked. Or your speaker volume might be turned down at the speaker (there's usually a volume control).

Personally, I think your hearing is going -- probably from all that Heavy Metal and Satanic Rock you listen to through your earphones, volume all the way up. I mean, don't you think an 800 watt amp is a little much for earbud use? Black Sabbath would sound the same at a level that didn't make your entire body look like a convulsion.