Kemper and External Valve Power Amp

I have recently bought a Kemper Power Head which I love and use all the time! I also own a Fryette Power Station which i use for various things. I have disabled the internal power section of the Kemper and have used the Fryette as the power amp from the monitor out. I am using a Suhr 2x12 open backed cab with Celestian G12-65's in. To my mind the sound is better. For live use it definitely has more shimmer and punch which I prefer to power stage of the Power Head. I also play bass and prefer the power head amp for that. I noticed that Michael Britt always uses a valve power stage with his Kemper for onstage monitoring while the main outputs go to front of house. Has anybody else used a valve amp with the Kemper and if so are there any tweaks that are recommended to compensate for the fact that it probably isn't as flat or linear as a solid-state amp that the Kemper was designed to work with?