just some thoughts.
it would be cool if we had a variac control in the amp section.
while we can independently tweak the pre and power sections for bias having a control to turn down power to the tubes across the board would be awesome.
also how about some tube substitutions. there are many products in the real world to let you run 7-15w tubes in your amp and push them to the edge at lower volume. this changes the dynamics of the amp. it would be cool to do this virtually as well.