The other guys nailed it.
Know the natural "flat" voicings of each amp (they're never truly flat).
Know the frequency centers of each EQ control.
Use that to your advantage to make them sound somewhat alike. Don't forget that the cabinets and room WILL have a significant impact on the result.
BTW... you're cranking the bass on your Ashdown to full? Your bedroom settings will not translate well in a loud, live setting.
Never be afraid to CUT, either - it can sometimes be the key to what you're looking for. Boosting isn't always the answer!