I've got the yba200-2 and I swapped out the pre-amp tubes for JJ12AT7's Best move I could have made. I put the 12AX7's back in the other day just to see how they sounded. They lasted 1 min and out they came.Mids on full. Range fairly low.
I'm really interested in swapping the tubes for JJ 12at7s and KT88s. I hear that'll increase the mids.
I'm thinking an EQ pedal might be on my GAS list.
Still, even with the lack of mids, I love the tone of my amp.