I just got a new Marshall Class 5 from Musicinas Friend. It's The combo with the old school looking block logo. I like it just fine. but I would like to change something on it and i hope you guys can help me. Right now it has an 8 ohm speaker internally and a 16 ohm extension speaker jack on the back. When you plug into the extension jack it disconnects the internal speaker. This is great if I want to run this amp through a 4/12 cab and don't want the internal speaker, but I have many other amps I would use before this one to power a 4/12 cab. What I would like to do is use the Class 5 extension cab in conjunction with the internal speaker in the amp. This seems doable as there is apparently already a 16 ohm and an 8 ohm tap on the output transformer. I ordered a 16 ohm 10" silver bell from Weber to use in this amp and I ordered the extension cab. What I need to know is how to wire this up to make it work so I can use the internal speaker and an extension cab without muting the internal speaker. ANY help here would be much appreciated.