I would not use audio at all as everyone has specific taste and your music maynot suit them.
Most prefer to not have any music at all as they could be in the office or at work and music could mean they are lazying around
Background music is one of the worst things you can put on your webpage... Not only everyone has different music taste, most people are already listening to music while surfing, your webpage's music will mix and interference with the music. And when loading the music your visitor's browser can crash if it's not a good computer. :x
How exactly are you implementing the audio? If it's through flash, I'd suggest having the ability to stop or change tracks.
Having audio run through your website is tricky. Like Cornelius said, people have different music taste and what you enjoy might not be another persons cup of tea.
I suggest that you should never use audio, it just makes the viewer of the site more annoyed and agitated. Background music makes "most" people close the site straight away. Considering the music file might take a few minutes to download its almost the cause of most bandwidth outages.. Big no no from me
I would not use audio. If I go to a site that has audio I automatically close the window. Here are the reasons why..
1. Loads Slow
2. If i put my son to sleep and forget to turn down the speakers it comes blairing out and wakes him up
3. Half the time I don't like the music and am not able to shut it off.
Audio will slow down the display of your page.It is very annoying for the dialup server because not only this will slow them down but they will get irritate because the sound may be repeated over and over again
If your creating a site for only few user who have a broadband connection then include sounds with you.But if your planning this to be open in public then this is a mortal sin in web designing.