Most of the bad reviews you hear from these are people using them on thier phones or computers without a headphone amp,an absolute must.These have to have a decent amp to get the best sound.
I recently bought a pair of HI Fi Man Sundaras,the best selling headphone out there.
The Koss Pro 4 AAs are superior in bass response and detail retrieval.
Sundaras have a wider soundstage,but are horrible with thin bass.I have both phones pictured.
I also compared the Pro 4AAs to Seinhiesser 599s,again,Koss comes out ahead.
It's interesting to note that Roger Waters used the Pro 4 AAs when he recorded Dark Side Of The Moon.
Another hidden gem by Koss is the pro4 xx,and the Pro 4 AAA I wish they would produce again.

I love the sound of these headphones. The clarity is outstanding. That being said, they are by far the most uncomfortable headphones I have ever worn. They are just too heavy. I cannot wear them foremore than 15 minutes. In addition, the plastic part between the headphones digs into the top of my head. I will never buy these headphones ever again.

I have used the PRO3 for well over 20 years, and finally needed a replacement. I upgraded to the PRO4 and they are just magnificent. The frequency response is, of course, better then most inputs, but on a really good system, these shine like the sun. I am absolutely thrilled with this upgrade. Should have done it 10 years earlier.

A perfect match of my 1973 phones except that this pair has no volume control and that s---s.

I’ve been a radio broadcaster for 32 years. My first choice in headphones has always been the Koss Pro4AA’s.
Sure the stations always supplied headphones for their announcers but as soon as I got my first paycheck, these were the first thing on my shopping list. The sound is great and the excellent isolation insures that you can turn it up without the danger of feedback. So, turn it up! You won’t miss a detail with these “cans.”