I'm very happy for you that eventually did bond with this amp. I understand why you gravitate to 53 and lean. A LP sounds best in this configuration. However for single coil guitars like my Tele, Strat, or Rickenbacker 330, the 58 and lush is the way to go!
For all you James Gang fans out there. I spent the last 60 minutes playing my Gretsch 6120 at the following setting. This nails the guitar tone in the song "The Bomber":
This amp is crazy loud. The suggested Bonamassa settings are not possible in a smaller setting (like my basement). The 12AY7 certainly did not sound bad ... it just took longer to break up. It's a great sounding amp with either preamp tube.