Definitely brush up on your soldering skills. You could potentially damage a circuit board trace by over heating your work. Remember, just because a tweak works well on one product doesn't mean it's going to well for everything. Mods can be very product specific.
schematically speaking
I have been toying with the idea of tweeking a cheap amp. Caps power supply etc. After getting a feel for it I thought I might move onto something of value. Are schematics readly available for amps such as adcom, sony, onkyo etc? Also I presume that I can replace a cap with a like cap of a different manufacturer?