Isolation transformer or power conditiner?

Isolation transformer-MGE UPS systems,conditioner-Powervar 300VA;I already have independent ground.

The isolation transformer will definitely help as it will keep all the hash on the electrical lines from other household items down to a minimum. If you use an isolation transformer that has balanced outputs that will help even further. Also, independent grounds can be a great help, but I recommend that you have this done by an electrician as codes and the safety of the ground is very important. Adding a seperate power conditioner to the CD transport and DAC will likely help too (although probably less than the isolation transformer). The conditioner will help isolate the hash given off by the DAC. You should use separate circuits for the DAC and the transport if possible. Could you let us know what isolation transformer and what conditioner you are considering?