I had come across this hybrid of putting the 3-flange ER-4 rubber tips on Koss The Plug or SparkPlug phones, plus a few other tweaks to improve sound quality (cover the rear vent holes with tape, add a tiny bit of foam behind the driver, and a tiny strip of foam over the sound tube). Has anyone tried this? If so, any tips? I can get the SparkPlug for $10 per pair (buy.com) and ER-4 tips for about $3/pair, so I plan to experiment. I'll report back; just wondering if anyone else has tried to tweak this combo.