I recently purchased a code 100h. I've noticed that with the cabinet simulation turned off, the amp is incredibly fizzy and bright. I am running into a 2x12 with Celestion Vintage 30s. Is there a way to tame this high-end shrillness without having to resort to running cabinet simulation through an existing cabinet?
Did you try do decrease Treble in PreAmp section, and Presence in PowerAmp section?
I think the amp is voiced to be used with the cabinet simulator switched on going into a real speaker cabinet so switching it off will have a dramatic effect on the sound.