Behringer EP1500 - EP2500

I am mainly using my EP1500 as a Bass rig poweramp.  I also use it in
small PA situation or to run the tops when bi-amping.  I also use it as
a subwoofer amp in my home theater setup (I like to have lots of
headroom).  I am building an enclosed rack to put all the amps and
stuff for my home theater.  Since I will put the Behringer in that
rack, I did a recoomended modification to it: I installed a quieter
fan.  The original fan is really loud for a home setup.

I noticed that the air flow is from the back to the front.  That's good
to me.  But why the hell is the air filter at the front then?  All the
dust can come in, but can't escape... great idea!

I'm I missing something there?

-- 
Frederic Gelinas