Bit late only a couple of years! anyway I built a twin cab with 2 Celestion 15w 8 Ohm in parallel I opened up the back of the V30 wow is it well built disconnected the horn speaker and the main speaker I mounted guitar jack in the back panel put the main speaker wires on it ,I left the horn wires disconnected. I had another guitar jack on the cab, used a proper head lead and WOW now I have a great amp the headphone jack still works and cuts the speaker out when plugged in. I also own A new Vow VT40X but I seem to go to the spider more way more and the Vox is a great amp so that may tell you how different the spider is now I did not use a isolating jack because I never intend to use that bad speaker so a good single speaker in the amp would be great as well but I would disconnect the horn speaker. cheers From Oz
