Summary: I normally don't write long or extensive reviews, but this product has really exceeded my expectations!
I recently bought a pair of NOS AKG K340 headphones from a Headfi member in Austria.
Pros: [With screen mod]: Exceptional detail, open soundstage, excellent instrument separation, excellent dynamics, speaker-like sound, a pleasure to hear!
Cons: Sort of uncomfortable, bass weaker than I like, hard to drive properly, mids/bass slightly slower than the treble., slight incoherence of mids/highs.
Summary: I bought the AKG K340 Electrostat-Dynamic System twice. The first pair was very worn out and sounded weird so I sold them after a while. I bought the second pair from Ebay, and this one sounded very different. I used the first pair with the Beta 22 amp which really struggled to drive it properly.
Summary: When I first began my career, I was looking for some inexpensive but good quality headphones for my personal reference. The K340`s were less expensive than the cream of the crop at that time, the Staxx system with the discrete amp, etc.
Pros: Long life, used in both studio, live sound, and for fun
Cons: after buying them new in 1987, the foam is a little worn, wire tension on the pods is a little loose
Summary: It's time for another review that I've been sitting on for a while. Writing a review of a vintage headphone is difficult at the best of times, and there are some strange features of the AKG K340 that are even more difficult to deal with.
Pros: musical, fun, stunning treble, no fatigue, forgiving
Cons: Requires monster amp, not especially detailed, a bit slow, slightly muddy bass, each pair is a bit different.