Hey everyone, I've had a problem recently playing some songs on my iMac. I have a pair of cheap Altec Lansing speakers attached, but regardless of whether or not they are plugged in, certain songs sound very strange. Mainly, the vocal line is almost INAUDIBLE. i've played with the mixer settings to no avail. Is this a hardware issue? Anyone else share this issue? Again, it only happens on certain songs. thanks! edit: the songs play fine on my ipod.