with the soldanos, a lot of people who use them seem to dislike the depth mod for some reason, which I don't think is on the hot rod. It is an optional extra on the SLO.
the SLO with the depth turned right down is meant to be the same as having no depth mod, according to M Soldano. I've tried the depth totally out like that and didn't like it. I like having the almost sub low end in there to warm it up.