[quote name='discreet' timestamp='1468937815' post='3094481'] 
Presumably you could connect the tone-shaper or Pre-amp of your choice into the Return socket, thus using it as a pre-power set up. If you wanted.  
[/quote] 
 
Yes, effects return or line in (jack).  I also use a Sansamp VT in front, if I'm doing a blues or jazz gig.  I think of the R800 as a power amp with eq on the front.  Works well with the old rack preamps, and it can just sit on top of a rack bag.  I'm sure it could also be mounted on tray if you wanted to get it into a rack case, but I would'nt bother.