Any ideas on how I can better the distortion levels on this Crate GXT dual triode 100 watt amp.
this, really. If you don't know how to answer your question yourself, you shouldn't be trying to tear apart your amp and risk ruining it to change the sound of the distortion. Turn down the gain on the amp and let the effect pedals do the work.
>dual triode (guitar amp)
>shows two tubes
Two 12ax7s is actually four triodes. Four triodes are used to build the entire preamp of a lot of iconic amplifiers (AC 15,30, tiny terror, countless fenders, the list goes on).
There are a number of ways to raise or lower gain, sensitivity (ease of creating distortion at the cost of headroom), asymmetrical clipping, hot or cold preamp clipping, and whatever else in the preamp.
That being said, I have no idea what Crate has built there. A great preamp can still be a pretty poor amp if the rest is neglected. Crate is well known for making a lot of cheaply made gear. When equipment is made to be cheap rather than to sound good, your tone suffers. ssguitardotcom is probably a better forum for this question where the members both understand tube and solid state amplifier design.