[quote name='xgsjx' timestamp='1398761309' post='2437234']
I'm gonna take a guess that to allow 3 cabs to be run, the amp can either run to a lower Ω than the 4Ω they state, or the cabs are a higher Ω than the 8Ω or 4Ω, or (most likely) both.
[/quote]
BGM tested the RC cabs and found the 2x10 to be about 10ohms and the 2x12 to be around 11ohms.
No magic involved, just TC playing around with numbers in order to sell stuff again.