PPI masters are good with the Suhr amps if you know how to treat them. Don’t think of the Suhr SL series PPI master volumes as a “true” master volume control like on a 5150 or Rectifier or something. Instead, think of it as a “Reverse High Cut” control. Increasing the Volume / Gain on a plexi means you add gain but lose treble and clarity as you do that. With the Suhr amps, the idea is that you start with the Master on 10 so it’s disabled, then you can turn up the front volumes until the gain is where you want (but the higher you go, the darker the amp will get overall) then edge down the PPIM until you get as much treble back as you want.
Unfortunately this means the control can’t be relied on to be a “true” master volume control, but what you get is much more useful for shaping your tone IMO. Well, as long as you have a good reactive load / reamping situation.