Something specific about the K271 is very synergistic with my ears. It's interesting what Superlux has done and I'd like to grab a model with similar signature to the K271 mk2 for comparisons sake, and disassembly/inspection. From innerfidelity's headphone graphs, the HD681 look almost the same as the K271 (smiley face is ok. It's the pattern in the highs that seems to matter):
Is it safe to say these will sound very similar?
Update: Yes, they sound just like the K271. If you like the FR/signature of the K271, these are cheap replacements that, lacking the special diaphragms the K271 has, may or may not resolve as well, but have incredible sound quality and clarity for the price. Despite being open and appearing like the K240, they don't sound like it and behave as the K271 do in every way. Notable differences:
Stiff rubber pads are okay - no velour included.
Bass is not rolled off so quickly. Not boomy or bad in any way however, and not too much quantity. High quality and analytical, and have a place as a studio monitor as the K271 have a name for.
No auto mute switches.
No removable cable.
For 35 dollars shipped I don't think this can be beat. Some will argue the 668B is the model to go for, but based on FR, it will sound honky and annoying to ME. K240 for example, do not sound right and have peaks and troughs that don't synergize with my ears, despite being very close to K271. Again, for a FR resembling AKG K271 precisely, save for slightly more bass (I would say, now a normal amount for recreational-analytical listening), these are a great backup/disposable headphone, or may be the budget panacea.
Edited by k00zk0 - 10/21/13 at 5:12pm