Quote from: mguzzo on May 11, 2021, 12:24:36 PM
My plan is to replace the 2030 with a 2040 and put in a larger transformer to drive a little more wattage.
As Phil said, it's not really worth it. The 2030A is already at its max with +-20V, being able to give around 18W. That's plenty loud for a guitar unless you are playing big venues, in which case the limit is the speaker.
The easiest and probably the most effective way to get more output is to add the output jack and hook it into a cab with a more sensitive speaker. Even a 2x12.
LM1875 could be a good candidate to get more power. But it will need a new PSU and probably a beefy heatsink. For now, this is probably "going too far" territory for me.
For bass, the preamp is too mid-focused. Perhaps the FX loop would be a solution for you so that you can bypass the preamp with its highpass filtering and drive the output directly with a bass preamp or pedal. But to be honest for bass I would just get a fender rumble and call it a day.
Quote from: mguzzo on May 11, 2021, 12:24:36 PM
what's the difference between adding a 1/4" for driving an external cabinet v. the headphone/line out jack?
The headphone output has series 1W resistors that limit the power to levels adequate for headphones.