What will raising the Va of atransformers provide?

I have a dual-mono custom built solid state power amplifer with a pair of 500Va transformers. The power supply is in a separate chassis/housing.

Is there any merit to increasing (upgrading) to upwards of 1000Va transformers? What kind of sonic benefits can this provide?

I realize in my lay understanding of amplifer design that this retrofit will likely require a cascading change-out of other components (resistors, etc.) as their requirements will have to be matched to the higher Va transformers.
If so, what are some examples of the better quality manufacturers? I am not concerned about price.

Scott