Ha! I have a cheap-as-fuck Pro-Co DI box and ironically have had the same experience with Radial myself and other's that are in the know.
I do like my D'Accapo ReampBox.
Do you have any isolated parts of the 5150 vs Herbet so we can hear the difference? Regardless, great sounding clip and I really need to try a 5150 sometime.
They're the only speakers I "like" to use. I have a V30 for V30s sake and a Redback, but neither capture the feeling under fingers and sounds that I expect like I do w/ my Scumbacks.