Toroids are a faris doughnut-shaped ring of material. Probably wrapping about
ten turns of wire from each speaker through ine should do the trick. You should
be able to get some 2 inch ones from Rat Shack.
Tom
Tom Brennan KD5VIJ, CCC-A/SLP
web page http://titan.sfasu.edu/~g_brennantg/sonicpage.html