If anybody has a DSL 15 and doesn't want to go to trouble of the Johnny Eggz mods, JJ makes a tube that does 70% of it if swapped into V1. It's a reversed 12DW7. A 12DW7 has one of the triodes the same as a regular 12AX7 and the other a 12AU7. A 12AU7 has only 17% as much gain as a 12AX7. However, if I recall correctly, the regular 12DW7 puts the 12AU7 side on the green channel. The reversed version will put the 12AU7 side on the red channel. If you only use the red channel and never use the green channel, any lower gain tube in v1 will help tame the red channel. But any lower gain tube applied to the green channel will gut the green channel.
The Johnny Eggz mods go beyond just controlling the excess gain of the red channel but also make it fatter, and warmer, but it's much more involved than just swapping in a tube.