Sometimes I like to do things just because I can... I have a fender frontman and I found the schematic here http://support.fender.com/schematics/guitar_amplifiers/Frontman_25R_schematic.pdf (http://support.fender.com/schematics/guitar_amplifiers/Frontman_25R_schematic.pdf)
Would it be difficult to hack in an effects send/return? From my limited knowledge it seems like you would just need a buffer or two before r55 by the power amp