Badlander 100W & Rocktron Xpression question

[ecl3rd]

Hello - I recently purchased a brand new 100W Badlander. Really enjoying the amp. However, something interesting occurs when switching from high gain to clean. I set one channel to clean and one to high gain. My primary effect unit is a Rocktron Xpression run through the effects loop. When I switch to the clean channel I get a surge of sound as if there's a electricity that needs to be used up going from high gain to clean. Another aspect is that, you can hear distortion dissipate, i.e., trail out when I switch from high gain to clean. I haven't experienced this with any of my other amps; Carvin 100W V3, Carvin 50W V3M, Soldano Astro, REVV G20, Peavey Valveking, Peavey Triumph 60. Anyone experience anything this?