It is easy to change the amp's tone by making changes in the power tubes and the small tubes if what you want is a different tone. I did. You can start with different KT88's or 6550's. But you've got to have a goal in mind.
You can increase clarity some by using a high quality preamp but I wouldn't spend my money on a new preamp just to get a different tone.
You can increase clarity some by using a high quality preamp but I wouldn't spend my money on a new preamp just to get a different tone.