The background noise should be "simple" enough to remove if you have a section of the sound file which contains ONLY background noise sans the music. The key to this would be to sample the ambiance prior to getting the music. Then making a noise profile, then using that to apply a filter based on that profile to the file to eliminate such noise. You do not need to sample very much noise, as long as the noise remains consistant throughout the recording it should not take long to eliminate. If the noise varies throughout the recording, then you may need to sample different areas to eliminate the noise.
If you are talking about noise from a power source. It should either be 60hz or 50hz depending on where you live.
Also, if you can isolate the noise to a specific frequency then you could always remove that with a bandpass filter