one channel louder than the other. need help

breaking in a new pair of vandersteen 3a sig speakers with bat vk3i,bat vk200 and ayre cx-7. all gear was purchased within the last 2 weeks, bat stuff used. set it up friday night and everything has been fine. today right channel is louder than left. disconnected and reconnected everything but problem persists. any suggestions? is there a way to test the output of the components?

thanks keith