FX Loop Hiss/Quieter sound.

Hello everybody, just upgraded my Kemper Rack from 5.7.2 to 5.7.7 and now my rig sounds a bit quieter with FX loop on than when it's off even with no pedals connected/turned on. The worst part, it now has a noticeable hissing sound when FX loop engaged, did anyone else see encounter this issue? Can also anybody email me 5.7.2 firwmare at [email='st.snowball at gmail.com'][/email] cause it seems to be impossible to find it anywhere on the web, also tried calling/emailing tech support, but didn't reach them. Thanks in advance!