I have two sets of Koss Pro-4aa headphones. My original transducers are apparently all that remain of my 1972 pair, after I sent that pair back in a body bag with $9 for s&h last year - great lifetime warranty. They look the same externally as the new set I bought ~five years back. The old transducers are more mellow, but still have excellent piano overtones. I sprung the headband on the newer ones - it helps with my large noggin, which is still too tight in the rebuilt units' headband. I left the new ones over a weekend "on" my Tivoli Model One AM/FM table radio - literally - that may have been too much. Maybe a few books would be better for the warranted pair. I like the Pro-4aa's because of their fluid fillled cushions - great seal for ambient noise. They are - like me - old school. My 'new school' headphones are thirty year old Sony MDR V6's - two pair of the same vintage. Sadly, they went through a dozen or more OEM Sony ear cushions before I discovered some great aftermarket units - no more walking around with black earcushion residue stuck to my ears! They have a pronounced bass - not as low as the Koss - but more midrange to treble - slurred "S's". Marc Cohn's original CD is a great source to evaluate headphones (Played on an Onkyo C-7030 and driving the headphones from my Emotiva A-100 BasX amp's front panel headphone jack.). The Koss seem flatter in response with a lower bass extension. Even the mellow old rebuilt ones reproduce the triangles well - as if 'out of the darkness'.
I've done a lot of shortwave listening over the last fifty-odd years - and the Koss Pro-4aa's are my favorite there, too. The closed back over the ear style pretty well isolates you from ambient noises - and others from you, too. The Sony's are closed back but sit on the ears with a lesser seal than the Koss'. The foam pads - a la Sennheiser used - have never felt or sounded 'right' to me. Actually, I find the sound quality, separation, and even sound stage better over headphones than even my Heresys!
JRT3
