This is the picture of my VHT special 6 ultra combo. I am trying to find out which 12AX7 pre amp tube is for the clean channel, and which tube is activated by the gain channel, or "ultra" channel. I have placed the tube jackets on the respective tubes for identification purposes. With the present tube configuration, I am loving the clean channel. I am trying to determine if I should try two Tung Sol or two JJ brand tubes.