I am currently looking for a way to shield 2 transformers in an amplifier I'm putting together.  (Specifically, AKSA 100)
I was thinking the magnetic shielding used for speaker magnets would make a good choice since they're round and I could possibly find one in the right size.
Has anyone tried this and if so, what's a good source for the shielding?  Is it something that's fairly easy to make?  
Ideas and suggestions for shielding transformers are appreciated.
-Carl