I'm no tube expert... but all those mods sounds like they'd do the opposite of what you want and make it cleaner.
Yeah the Plate resistors need to be higher, I am very sorry I was very tired.
The plate resistors should be
INCREASED to something like 120-180K,as high as 220K,the higher the value the more gain the stage should have.
The lower cathode resistor biases the stage warmer,the higher cathode biases the stage colder.By biasing the stage out of its center area you get clipping much easier,especially when the gain is increased.(raising the plate R's)
By biasing the stages cold then hot a clean booster at the input can really make it sing.
One thing I read today to keep in mind, is to make sure you don't exceed the tubes dissipation.
The voltage drop may be from lowering the second stages cathode R as that value lowers you dissipate more.
Again I am sorry about the mis information on the plate resistors.
I would start by raising the input stages plate resistor to 180-220K ,with the original 1k8 cathode resistor set on a 10KL pot (so you can find your sweet spot) bypassed by a .68 - 1 uf cap.
The goal at the input is to get as much gain as possible to overdrive the second stage.
Then you can raise the second stage's plate R to get more gain too,but bias it hotter by lowering the cathode R (a 2-5KL pot should suffice to find best value)bypass the second stage cathode with around a 10uf cap.
Two stages are hard to get more than mild OD with, most 2 stage amps rely on the power stage for saturated distortion.
If you could add a cathode follower at the end of the pre amp feeding a tonestack/or not that would add some compression of the signal.
Not more gain but you would squash the signal/sine so as to cause distortion at the top and bottom of the voltage swing.
I should have asked what type of distortion you were after,
Before giving my input and drafted a rough schematic to check my suggestion(lesson learned)
I will draw up what I am describing and post it so it is clear.
