Boss VF-1 Effect Processor

i wonder if any of the group has a similar problem to myself.
as being a guitarist i use the vf1 in that enviroment with full range 
multimedia amp and speakers(home use only).
i find that the preamps are very fizzy,this is using line out mode 
and with mic level on 100.
i have also a line 6 pod,korgax1000,vg8ex,gr33 these however sound 
really good through the set up.
is this common with the vf1.
does anybody have any ideas on there setup.