I've had another go at the amp before boxing it back up for a return to Andertons.
I can only come to one conclusion that it is just a guitar combo marketed as a bass amp. There is no deep bass, or even mid bass to this combo. Even with the bass maxed and the treble turned off I can't get a deep usable bass sound. Tried my P and Jazz with the same results. Even at moderate volumes the cabernet rattles and the speaker farts. I really don't understand what this amp is doing.
I was so looking forward to getting a 50w combo that could be used at quiet / medium volume gigs. No one is making this.
Oh well the search goes on.