A few years back, I bought some (cheap) 12" speakers from Radio Shack to replace the woofers in my wife's stereo system. These speakers had a feature that would be really cool in a bass cab: each speaker could be wired for 4 ohms or 8 ohms. There were three lugs on each speaker and depending on how you connected to it, you either got 4 ohms or 8 ohms. This would be a nifty feature on a bass cab- your amp could always put out full power regardless of whether you were running one cab or two cabs. I figure there must be some major drawback to wiring a speaker coil this way, like a loss of efficiency or frequency response or else SOMEONE would have done it. Any ideas on this?