Right Channel Lag

Never had this happen before. Hoping someone can tell me why. Whenever I use any of my sources, CD, TT, or tuner and begin to turn up the gain, sound always comes from my left channel speaker before the right. I've switched interconnects and swapped right channel for left. Then, it is the right (formerly left) channel that comes in first. Where do I look to source this problem. I should mention that after volume is at normal levels there does not seem to be an obvious imbalance between the two channels.