Kevin at Upscale Audio sells "Isotek" power conditioners. He has YouTube videos for two of them. He has a meter that says that one of them, the "Aquarius", brings line noise down to zero percent without limiting dynamics. Worth a look?
https://www.youtube.com/watch?v=peDcpldHYvc
https://www.youtube.com/watch?v=peDcpldHYvc