Good idea or not ? Maybe I'm wrong, but the Sheffield is based on Greenback and a lot of people says it's not a bad speaker and it's supposed to work well with 5150 (as Peavey intended). I'll use a 212 combo converted to head (60 W) into a 4x12 cab (100 W) and only for decent volumes (recording, not gigging), so I'm not worried about nasty cone breakup. What do you say ?