I have two cabinets that were designed for combo use and only have a male 1/4" plug coming out the back (short cable meant only to reach the head). Where can I buy a 1/4" female to female adapter plug for speaker cable use? Only few I have found seem to be for instrument cables. (I checked Amazon, Musicians Friend, Reverb, and Monoprice) (and yes, long term plan is to remove back plate and wire up the cab for speakon connectors, etc - but for right now I'd like to just try the cabinet out with a different head. Cabinet is an Aguilar GS212 - but the combo one.) Thanks!