you can get shielding kits from www.stewmac.com. Id get 2 as when I did the inside of one of my strats I ran out halfway through.

The real problem probably lies in your setup.

A HiFi is tuned differently to a guitar amp / speaker system. A guitar amp is engineered to output the frequency range of a guitar. A HiFi system has to cope with a much wider spectrum of sounds.

The wah is effectively cutting and boosting particular bands of frequency and with the boost in signal come a boost in noise.

A guitar amp, relative to a HiFi exhibits a natural cut in bottom end and top end frequencies. Because you are amplifying and reproducing a broader spectrum of sound using the hi fi stuff, up comes the noise.

My advice, get a pod and a floor board, run that into your computer or a dedicated guitar (or stereo amp if you have to) and you have power to play with.