I have been through this and Bednobs is right, contact your local Environmental Health agency. Also contact the Housing managament as well just so that they are aware. I would recommend starting a Noise/Nuisance diary as well, noting down the times etc of what the noise is and how loud etc.
You will probably end up (as i did) having a Sound recorder installed in your home for probably 10-14 days recording the decibel levels etc. It is very intrusive and i had to have it done twice as the first machine failed to record anything as it broke!
Also speak to your neighbours to see if they feel the same way, strength in numbers is a far easier way to tackle these anti-social idiots.
All being well the Environmental Health Agency will probably serve a Noise Abatement notice on the tenant and then if it continues either seize the equipment/Cd's etc or Serve an Eviction notice via the Council.
I wish you luck and hope that it all goes well.