MCL,
I would also look into using a 14 AWG cable with the new speakers. I got 250 mts role from Cables To Go and my HT system sounded much better than the stock 16 guage I was using originally.
I will take a guess and say unless you have some long runs, the improvement was most likely due to some slighlty oxidized connections and the new wiring simply eliminated the poor connections, but the 14 AWG suggestion is dead on. I wouldn't wire up a system with anything less, although I was using some very old 16AWG when I first hooked up the M80s and then switched to Axiom's 12AWG, I really couldn't hear a difference.
