First of all akg k701 are not just for audiophiles! They are reference headphones for starters. Also says on the tin! Second you mention that because of their impedance they are not good for %98 of professional equipment. I hope you are joking here. Professionals have headphone amps. If you want to use them on your macbook's output or your cheap interface headphone output you might be out of luck and you might have never used them to their full potential. I have personally sold them as they were not what I wanted when I had them but I will def buy another pair at some point. Also I got them for a steal price of 100 pounds and sold them a year later for 160 on the bay. Listening to acoustic and classical music on them is just pure heaven. I have also owned dt880, hd650 ( I prefer the hd600 to them) and my current big love is the Focal spirit pros. Best translation from any other headphones I ever used. If it sounds great on them it sounds good almost everywhere else. Also their low end is just crazy amazing. But for classical and acoustic I would still pick the k701. Also I mentioned on my initial post the need for a good headphone amp with them.

 

Last edited: Dec 13, 2015

It's also stated on the box, but what does it matter really?

Output impedance has naught to do with MSRP of audio interface. Even famous RME Babyface is rated 30Ohm, several Neve desks in broadcast studios are rated 30-50Ohms. It's just one of the ways to protect headphone out from short circuit, and a sort of simplification, as it's possible use speaker outs through such high resistor into high impedance headphones. Tube amplifiers are totally out of question without output transformer.
Professionals might have headphone amps, but some don't. Again, in broadcast studios one just plugs headphones into mixing desk and that's it.

I find that really hard to believe. I was selling mine for 90 pounds for 2 months on ebay.co.uk and nobody was interested (pristine condition, recabled and balanced). Only when I took them to ebay.com, someone from Canada finally placed an order.

Yes you did, but "good headphone amp" tends to be vague for most people. Tube amp might be considered "good sounding" and some of them surely are, but pairing tubes with low impedance cans is not the right way to go.
K701 needs either solid state or op-amp based amplifier with maximum of 5Ohm output impedance and high current reserve (50mA) with lowest distortion possible.

@AHM Sorry, I don't have M50 and quite frankly don't plan on getting any new headphone soon. M50 are also only 38Ohm, so it'd pose damping problems similar to K701 if driven without an amp. May I ask which version of DT880 did you happen to purchase? Honestly, I had to return the 600Ohm DT880 as there was treble peak around 9kHz, therefore completely unsuitable for production.

 

Last edited: Dec 14, 2015

@Andrew I have 32ohm which I couldn't resist because of the bargain price and a trustworthy family friend who didn't like them due to the 'uncoloured' sound as he wanted Dr. Dre type of sound and was very disappointed in purchase. So I was like no worries sir . Before that I tried 701's but there was something not satisfying. I am not a pro, but I trust my ears. But thank you for very learned information about impedance etc. My next buy will be based on what you said.

 

I sold mine September of 2010 for 160 plus shipping on .co.uk in fact they sold pretty quick! For a while back thenthe cheapest you could find them was at thomann for 190/200 pounds. I thought it was good timing and it was. The market was not as saturated as it is now as well. There was more hype about them back then on forums etc.

 

Actually I'd update my previous statement and include AKG K601 in my recommendations list.
Side by side, K601 seems superior to K701/702 in imaging, resolution, precision and bass quality.