Just received an 8Ω GK410MBE to use as an extension cab for my GK1001/210 combo. I don't seem to be able to connect a 1/4" speaker cable into the ext cab input from the 1/4" 540w outs on the combo's rear panel. There is a speakon input in the cab and that is all. Is this for both speakons AND 1/4" cords? When trying to insert a 1/4" cord the fit seems awful tight. Is this normal? The ad in Musicians Friend states; " Speakon and 1/4" inputs" under "Features". Don't want to force it and break it right off the bat so thought I'd ask you guys. I thought GK cabs came with a speakon speaker cable as part of the sale - but the shipping plastic in the shipping box had a hole torn in it and I imagine it was removed.