- 2,015 Posts. Joined 3/2008
- Location: Toronto, ON, Canada
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The Pro/4A isn't very good at all. That's all I know.
The 4AA is better, but still not the best.
The 4AAA is the best of the three, and I actually have it. It has a natural, balanced, and detailed sound, with slightly rolled off treble. The soundstage is absolutely MASSIVE and the instrument placement and separation is really awesome. They have a performance-like quality to them. Definitely recommend them.
Be CAREFUL though: there are many different drivers. The Series 1 driver sounds the best, and is symbolized by a black AND white diaphragm. The Series 2 driver is the same shape, but all black. It's slightly darker and has worse treble and a slightly forward upper midrange. The Series 3 and 4 drivers are still in production and are for the new 4AA and the 4AAAT respectively, and they're by far the worst sounding. The Series 3 driver is also found in the 4AAA Plus model.
You can't tell between the series 1 and 2 drivers on an auction photo. It's too fine of a detail; you have to look very closely at the outer part of the driver in person. You can, however, tell if its a series 3/4 driver because the headphone will have a different looking baffle plate. This picture is of the driver to avoid:
Hope this helps.
EDIT: ****, I just realized this is 2 years old. Oh well.
Glad to see some love for the 4AAA. Most of KOSS's new offerings can't even come close to touching the original 4AAA.
Here's an FR graph of the 4AAA (series 1) and the 4AA (series 2). There's a major resonance in the 4AA and a much steeper treble rolloff.
Additionally, the 4AAA isolates better than my DT1350, which is insanely good by itself. It measures in at -19dB for isolation. I'd guess the 4AAA to be about -22dB based on that.
Interesting stuff!!! Gonna go check out my Pro4AA's to see what series the drivers are. My cans are a little different than the ones that are in production now, there is metal on the ear cups right behind the ear pads. Thanks for the info!