Build quality - I can say that in the 5 years of use the only thing wrong with these headphones were the pads falling apart.  And there is a very small tear in the cable sheath near the Y connector.  I have never got the gradle sound that some people get.  So to me the build quality is great for the design if you treat them well they will last a long time. They have plastic cups with plastic and metal gimble and metal headband that is covered in leather looking plastic material, the cable is very thick and sturdy. If someone wraps up the cable they will see the cable sheath tear away from Y adapter and expose the cable, Please do not wrap/roll,mistreat this cable and it will last a long time.
 
Audio - These headphones will accentuate the highs very well and that can be uncomfortable at times, I only experienced with very loud volumes though.  The bass in the SR80's do not have much impact it does go low it just will not slam.  The mid range sound is nearly flat nothing that will stick out as bad or good they match the headphone very well though.  If you like to listen to live/recorded guitar solos try these as they really do love that kind of music. I would not use these if you are looking for slamming bass they just do not perform this at all. 
 
Comfort -  I generally do not like on the ear headphones I wear glasses so they can be uncomfortable. The original pads did not work well for me so I got a set of G pads and it was more comfortable but it does change the sound slightly for me I liked it but some people would not.  These headphone bands are just a thin piece of metal if you are careful you can bend it to be comfortable for your head.  
 
Over all - Good sound, easily modified, Can adjust the comfort for your head. Can have some issues with the cable and sound if mistreated.