Glad to see SOMEBODY who isn't using Recto cabs with V30s. I don't get those for Marks at all. I bought a horizontal Recto 2x12 for my MkIII head and was instantly disappointed. Probably the first big mistake I've made from blind online purchases. Something about the fizzy top end ruins it for me. I'm on a quest to find a vertical 2x12 like yours!
Were the v30s broken in? I've only ever heard fizz on the top end of them when they were not broken in, personally. They all smooth out quite nicely, but especially the Mesa ones and the older UK ones.