A lot of people don't know this but most important is to shut down the internal microphone of the laptop !!!
Mostly the ones who rent out their projectors( the picture and movie guy's and girls), yes, the one's always "spoiling your light effects with their 500 watt halogeen construction light on a wooden stick
) have no clue about this and put their items close to your speakers with their internal mic still working..
Guess what?
Who has feedback all the time?
Rule nr. ONE to projector rental folks:
"Shut down the internal laptop mic to avoid feedback in the sound system !!"
2: make sure that their volume is about 50 % in their laptop to avoid clipping and distortion in your incoming signal.....
3: make sure that their internal sound card has no effects on like echo etc...
4: make sure their equalizer is flat so you are the one to control the tone and not them ! If their signal is to much bass you are the one in trouble...
If they don't know how to fix their settings ask them if you are allowed to do it in their laptop....
Ps, this goes also for your own laptop, no internal mic on, no effects in the sound card and flat equalizer.............
My 2 cents...