So in the mean time, any impressions on these?
 Its these bad boys, except in perfect condition, except for that one wire.
I have had an original pair of K-6 in working order since around 1975! They were intended as hi-fi listening phones but are as good as any, including the standard studio Beyers, for live and studio monitors. The only modification has been a modern Neutrik jack. The oil-filled ear-pads give excellent isolation. They are heavier than most and not very stylish but are comfortable and do not colour the sound. There's not much to go wrong except broken connections in the cable and the ear-pads falling off. The ear-pads are a shrink-fit and can be made to go back on by heating with a hair-dryer.
I bought a minty Realistic Custom Pro from a thrift store for $2. They are based off the K/6 and have the koss logo on the side, sorta hidden. They seem like the same headphone, but the realistic custom pro is ported with a silver vent. Is the K/6 ported too?
They put out a good quantity of bass for their age, not very good quality though. The mids are recessed and echoey as mentioned earlier. The detail is adequate for general use but not critical listening. The highs dont really exist above 10,000 hz. They actually sound decent for their age and original msrp. Overall they are not audiophile quality or anything special, but they are not offensive sounding. They are good throw around headphones for $2-$5. They are built very sturdy. I wouldent pay more than $10 for them though. At that point just buy a ksc75.
I was just given the opportunity to review a pair of Sennheiser HD 598's. In a word, amazing. But mainly, after 30 years of earbuds and cheap Sony cans, my first pair of real phones came to mind immediately- the Koss K6-LC. I don't even know why I remember the number, except they were probably bought with a lot of paper route money. Not much to compare to in 1972 or so, but I used them to death. The foam on the headband began to decay, the coiled cord showed signs of too much abuse, but worst of all, the by-then hardened vinyl that made up the earpads began to dry out and crack and basically disintegrate; it was time to move on. I think the volume control failed too, and I am sure I replaced the plug a few times. They may have been an early pair, the photo at the Koss museum page showed a slider, mine had a mini-pot. I never throw anything away, they may still be tucked away in a box somewhere.