M, yes that wire is too thin, but it isn't making a huge difference. When the 2500 was doing the calibration were the sounds coming out of the surrounds? If so, despite the thin wire, the volume would have been calibrated to a high enough level to balance with the other speakers. Keep in mind that the surround channels often have little going on in them and aren't always "on", but if there's nothing, something's wrong.

-----------------------------------

Enjoy the music, not the equipment.