Actually, I think part of it might be because of the stock Fender speakers, because I ran the guitar and US Steel pedal through my music teacher's bass amp (which is a Kustom bass amp, equipped with a 15" Celestion speaker), and it sounded absolutely amazing. I didn't even need to roll the lows up all the way and back off on the highs on the pedal. I also haven't been using the Silver Dragon lately, and it's still quite bright.
So I think I need 15" Celestions now. Only problem is I'd have to modify the frame of the combo amp to fit them, or get a 500-dollar extension cabinet. :|