I won't masquerade as an authority, but the OTS is not a high gain amp.  I don't necessarily like the tone either with the overdrive and PAB engaged.  Too thick,  saturated and boxy sounding.  Are you using a D'Lator in the loop?  You would be surprised how a  D'lator wakes the amp up.

My OD trimmer was set at the factory at about the 9:45 position just for info.

For me I'd be hearing a 'mo better tone hitting the front end with some pedals.  For example RC boost > BB Preamp > Zendrive with a D'lator in the loop.

I haven't as yet found a use for the "jazz" setting (too weak) or with the PAB engaged (boxy sounding).

Jim

Steven,
   No expert here either, but using the volume in the preamp helps the OD significantly.  Its been written about by others but I thought I'd mention it.  I go around 5 for buckers and 6 to 7 for my strat.  It doesn't need as much gain to sing with the pre amp volume up. YOu can temper the actual volume with the ration and power amp master.
   I've run into the fizzy when playing with the settings but can't remember how or what the dial were at.  I have successfully dialed it out.  Also I have an outboard OD trim adjustment so I get tons of variations.

-Casken

glad this topic is alive.
I was experimenting as well. adding a bit of bass (6 or 7) seems to help a bit.

I usually set my volume and gain to 4 with my Tele and Strat. With humbuckers I need to turn the volume down to 3.

I'm sitting here playing right now ...it seems to me that you can dial out more of the fizz by setting the amp for a little more gain that you would normally use and then back off the guitar volume BTW...I'm playing a Les Paul with a burstbucker 1 in the bridge position

You might try a lower gain tube in V2, that's what I've done & I'm really enjoying the tone.  I think I have a NOS JAN 12AY7 in there, or a 12AT7.  Some might say that the amp sounds best with 12AX7's, as that's what HAD put in his builds, but tone is in the ear of the beholder, and its easy to change back if its not for you.  Good luck.

"Louder=less fizz?"

yes...I've noticed that too and that's another reason for "riding" the guitar's volume... If you think about it the first "stage" (tone, gain etc...) is the guitar.  With more gain on the amp the guitar's volume acts more like a tone control IMHO.  crankin the amp and playin with the guitar volume is just another way to manipulate the tone.