Koss "the plug" ... bought from an eBay seller, and uggghhh... I ended up destroying them, as I wouldn't foist bad sound like that off on someone else.
I'm always looking for quality, budget sound. After all, it's no surprise when $500 phones turn out to be good; when cans costing less than $50 turn out to sound even acceptable, that's cause for celebration where I come from.
I still remember that awestruck feeling when I slipped on my first set of PortaPros; I couldn't believe the tight bass, the good freq balance, the imaging. So when Radio Shack put the SparkPlugs on sale for $10, I grabbed a pair.
Call them the anti-PortaPros. Sloppy, bloated bass, no detail in the midrange, and no highs at all. Add to this a complete lack of acoustic isolation, and you have yourself one squealing pig of a lousy headphone. After trying them with Er-6 tips in the vain hope of hearing some improvement, I threw them away.
Oh well. They did come with a nifty little storage pouch. I now use it as a change purse.
I'm keeping an open mind about the KSC75s.