I bet koss would fix them or replace them if you wanted. I had some old 4AA's and they had an issue like 25 years later and they replaced the whole set with a newer set .   They dont know you got them 2nd hand . 

  Like  a previous poster said it's probably a power issue .  These sound amazing powered by a normal stereo receiver  . They have punch , mid range and upper end .   I don't use them on a mp3 player or phone for that I use koss atxpro  headphones which seems to be ok powered  by an ipod.

   KOSS PRO4S      Anybody  buy or listen to these yet .  Would be interesting to  hear a review on these . http://www.koss.com/en/products/headphones/full_size_headphones/Pro4S__Pro4S#Reviews

  Koss is the only company that I have seen  that will back all their phones for life no matter if you just break them.  I have had 2 or 3 pairs replaced with no questions asked.  

   Plug them into  a normal stereo amp  and they really sound awesome.  Have them plugged into a Onkyo amp with  a 24  band equalizer behind them.  They sound amazing specially on a clean vinyl record .   Can you say detail ??   

    Why would you lose anything?  You use the equalizer to make them sound the way you like it to sound , that's what equalizers are for.

  I can only say I love these headphones using them plugged into my Onkyo amp with a equalizer behind it .  As I sit here listening to  Montroses  "Space Station Number 9 " .  This is a sonic experience . These things rock behind a real stereo amp .

Quote:   To say nothing they are guaranteed for life against anything .vBreakage , you sitting on them etc...  Koss is excellent on that too. They replaced a 30 year old pair of pro4AA's for me with no questions asked.

Quote:   To say nothing they are guaranteed for life against anything .vBreakage , you sitting on them etc...

  I would imagine people who use the ear "buds" are even more prone as with those the sound is almost right on the ear drum .

 Yeah they all seem to do it , if people buy it and it makes money , whatever.     http://www.koss.com/en/products/headphones/full_size_headphones/RUK50__RUK50_Full_Size_Headphones#/?color=428903bea5c54c24bb8d8f6d8e6c5cbd Quote:

Quote:  That is correct all Koss products carry lifetime. And they will replace them no questions asked, have done 2  pairs of ktxpro's which have a inline volume which wears out after 3-4 years. 

Quote:       If you think it sounds like that it is your source . I have these and they sound fantastic.   Granted I am not running it thru some Sansa clip and  I am using them thru a real stereo receiver.T he sound is the best headphones I have heard in this price range .  The only way to...

   Koss pro dj 100 .  About $80 , with lifetime warranty  against any kind of problem.

Koss  Pro DJ100 .   Great cans for like $60-80 .   Lifetime warranty for any kind of breakage, just send them back anytime and they will repair or replace them. Usually they just replace them . 

  I have a lot vinyl which to me sounds best . Also have a lot of cd's which seem to vary a lot in  sound quality from some that sound horrid to others that were done right and really sound very good. I have a audiophile Marantz CD player to play them on .  I have some itunes  and ripped cd...

Quote:   Yeah just what I want more radio waves sitting on my head, I'll take cables...

  Yup  have a 10 band a side hardware equalizer hooked to my Onkyo stereo .  Makes my speakers and my Koss Pro DJ's  sound amazing . 

Audio-Technica ATH-M30 Professional Studio Monitor Closed-back Dynamic Stereo Headphones . Currently $44 on Amazon .

   I 2nd the Koss djpro100 .  Have the DJ and they sound great with decent bass and very clear upper end.  Best cans I have owned and they have a lifetime warranty against breakage of any kind. They are very good at replacing faulty units even on their low end phones that cost $20 .

Koss pro dj 100. You should be able to find these for $70 or less . Great sound across the spectrum. Search for previous discussions on these headphones..

  For a real sonic treat plug the DJ100's into a good stereo  receiver with a 12 band equalizer . They sound phenomenal.  

  I think the DJ"s require an amp of some kind  but if you get the right equipment behind them they are amazing .  I mainly use them on a normal stereo receiver and a 12 band equalizer.  They have real good punch and the mid and high end just sounds amazing .  Just got a new Audio Technica...

Quote:   That would say the speakers are lacking in the upper end if you don't hear the scratches but do on a good headphone...

   I am going to tell you Koss Pro DJ100's  about $80  .    I have a Onkyo stereo receiver and a 12 band equalizer behind them and I am like you a classic rock junkie from the 60's and 70's . Have a lot of vinyl and cd's almost all of it classic rock and music from that era .Most of my vinyl is...