I own both the scl4's and the se 420's, my scl4's have a short in the cord near the plug, causing one ear to go out, so I bought the se420's this past summer. The se420's have a more fuller sound, but the scl4's are more...accurate. they have a better sound stage than the se420's. Yet while the bass is more accurate in the 420's, it's overpowered by the mids, making it less present, while with the scl4's I can make outthe bass better and "feel" it more so. Don't know iif what i wrote makes any sense, but to put it like this I'm going to bh tomorow and getting a new pair of scl4's from bh even though my 420s have nothing wrong with them (the first pair of shures I've had to go the stretch of six months) As to why I don't just send the scl4's i own back to sure for replacement, this is my third replacement pair, figure i got my money's worth out of three pairs and their on sale for 150 at bh so it won't hurt me much.