yes, i rang them and they said it's ok to do that. i asked the same question on this board, as many others have done so before and after me, and the answer is always the same. some say you can do it without a problem, some say you can't. i'm not a technician so i don't know the correct answer, but after some research, apparently what might/will hapen if you run an 8 ohm cab from the 4 ohm tap, is that the valves won't last as long as they normally would. one user on this board also has a V6 and he said he's been running it for a while like that and it's fine.
valve life is not something that can really be measured, just too many variables affecting it imo
i'm just as confused as anybody else with this (or similar) problem. i would really like to know what the technicians, and by that i mean the people who design the amps for ampeg, orange, mesa boogie, marshall,and all other valve amp manufacturers, have to say about this.
anyone here know someone who works for them?