Time for a Darwin Award- surely paper towel/ filter will only not do damage if there's forced ventilation ie fan. Just put a dust cover over when you're not using stuff and take it off when you are. Mind you I suppose covers can cause scratching on the outside- surely a case of common sense.....
heat
i only use my stereo on sundays for 6 hours. i recently started to put paper towels above the air vents on my pre amp tuner and power amp to keep the dust out. i have a mcintosh mx132 and mc602. is this a bad idea? i know heat is the worst enemy for electronics but i don't play it loud anyway!