I'll probably become the devil's advocate in the eyes of many, but I don't really care. I'll simply state an opinion.
I was in the market for a pair of AKG K240 and stumbled upon these - Superlux HD681 (similar to AKG K240 in appearance). They didn't cost much (25 euro), read some good things about them, the "risk" was very low so I've bought them.
A few days later I bought a pair of used K240DF with the intention of comparing the two and selling if necessary the "bad one".
Upon receiving them the fit and finish is not something to rave about, but it's more than reasonable for the price. I've had costlier Sennheisers that were much worse.
I understand the drivers are proprietary to Superlux and they've been manufacturing OEM products for AKG, Sony, Beyer, etc.
They have patents on what they produce and from a legal standpoint they're a genuine manufacturer.
I'm a straightforward guy, so that works for me.
Moral/ethical debates and issues are not my thing. I'll let others beat it to death.
Although the exterior design is similar to K240 the sound is NOT.
By that I don't mean necessarily bad, but different.
The sound signature is similar to a loudness effect (bass and treble), but not in a disagreeable way.
The AKG K240DF is all about the mids and mid-highs and communicates music in a different way.
It's difficult to call one better or worse because they both have qualities the other one lacks.
The Superlux' bass response is fuller and delivers more impact (without being overbearing). They also seem a bit more dynamic and punchy. The soundstage is slightly narrower but renders depth a bit better.
The AKG K240DF has a smoother sound with slightly more detail and better soundstage width. Imaging is a mixed bag. The AKG tends to focus better the forward instruments and the Superlux the background ones.
As a short conclusion I'd say their different cans for different tastes and music. The Superlux is more enjoyable to listen to when playing amplified music (rock, electronica, blues, etc). And the AKG feels more at home with acoustic music.
One last note is about modding the Superlux headphone. There is an entire thread about that on rock-grotto, so feel free to read/participate.
I've modified mine with a better (starquad) cable, blue tack dampening on the cups and drivers and a filter to balance the highs. The sound is improved and I decided to keep them.
To my ears they are in no way an inferior headphone to the AKG K240 or other headphones I've had or listened to in the sub-100 euro category.
To end this (boring) message ... feel free to give them a try. If you approach them with an open mind you might be pleasantly surprised.
(If not ... it doesn't really matter now, does it?)
PS:
Rock-grotto link
