I upgraded mine with the new Firmware - V1.33.
You'll need a "Null" Modem Cable to do the Upgrade.
and you will need to download the "Uploader" first.........
Just follow the directions at the Fortec Download section for the Merc II.
http://www.fortecstar.com/downloads/index.asp?products=84%2C1
I run mine thru my Harmon Kardon AVR 435 Reciever with no problems(leaving it at the "ON" Position)