Mcintosh solid state owners, I need a small favor

Hello,
  I have my MC452 for 3 years. I have always used Unbalanced cables to the Amplifier. So, about a month ago I switched to XLR's. But, I never flicked the Balanced/Unbalanced switch on the back of the Amp. I forgot.

 So, here is where I need the Favor. When I switched the switch, while music was playing, I noticed a big drop in volume. I put the switch back to unbalanced and it got louder. So, I have XLR's connected and threw the switch and the music got lower? Put it back to Unbalanced and it got louder?

 Maybe someone with XLR's connected can try this? And let me know if you get the same result?

 Maybe someone else can explain why?   

 Thank You