I also had a roadgear back in the days (Rd900 in particular) and it's not the electronic tune is mentionin'
Tune, here's what you're lookin for: http://www.ibanez.co.jp/anniversary/...t_id=283&now=3
You got Ibanez own carved soapbars, and they started on your model (Sr400) then were adopted on Sr300 after Sr400 were dismissed
You got two concentric pots: bass (bottom) and treble (top) as you know the first one you encounter from pickups to the bridge is volume, the second is pickup balancer
The last one, in front of the stacked one, is the socalled style sweeper
Keep volume at full, balance at center detent and do the same with both bass and treble: then turn last knob clockwise or counterclockwise. In a sense you'll perceive more midrange (like the rolloff switch on Ibanez Soundwave combos) for a fingerstyle kinda playin', in the opposite sense you'll perceive a midscoop (enhanced bass/treble, less midrange: like the shape switch on Ibanez Soundwave combos) for slappin'!
hope this helps