A bit of an introduction, I'm kind of a vintage headphone nut and I've been using the KOSS PRO/4AAA (original, 1976) for quite some time now, a headphone I still believe trumps most modern options in the $1-200 range effortlessly, and can get even better with modifications.
The 4AAA has been out of production for quite some time, but KOSS made a successor, the 4AAA Titanium or 4AAAT, and it's been on the market for a good 6.5 years now at a price of $150. It features the same driver topology as the original PRO model drivers, with better magnets and a titanium coating on the diaphragm (unlike the 4AAT, which uses a different driver entirely). Most people cite it as being nothing like its grandfather, and go as far to call it harsh and bassless. The general consensus is that they're simply bad. Very bad.
Since the shell is fully open I decided to ask my friend for one for Christmas, for a DiY project. He apparently found one for dirt cheap on eBay and I just got it. I have been listening to it all day.
... Exactly why do people say these are terrible? They're a lot harder to drive than the original but they sound almost completely identical in frequency response, except the bass and treble extend farther. The transients are drastically improved and they're far clearer and more controlled. The 4AAA has more aggressive and out of control highs, the 4AAAT is far more mature sounding and the actual detail and clarity is superior even though the 4AAA may seem to have the upper hand at first listen. Furthermore, the 4AAAT is unique in that its the only sealed AND open design in existence, so essentially it has the same speaker-like bass heft and impact of the original 4AAA (which it was renowned for) with a very open sounding soundstage to boot. They're literally a straight up improvement, and this is comparing them to a <HEAVILY> modified 4AAA that has the rarer series 2 drivers (which are slightly better than the much more common series 1) and have every singe shred of performance squeezed out of them as possible.
They aren't end-all be-all, but come on, this is a $150 headphone we're talking about. Are they colored? Yes, heavily. Are they easy to drive? Hell no. Are they built as well? Not even close. But they are most certainly not terrible. I can understand not liking their colorations, but if you already DO like the 4AAA (which many people do), hating the 4AAAT makes absolutely no sense to me. The original is like a spunky, bombastic, out of control kid and the Titanium is like the same kid, all grown up and more proper sounding. It's the same classic KOSS coloration with modern technicalities and refinement.
These cans are great, especially at the price range, and it really irks me to see them get tossed to the dirt like this seemingly without rhyme or reason.
EDIT: After spending a significant amount of time with these I'm noticing a very odd sounding veil on the midrange that makes them a chore to listen to. It's not fixable with EQ so it's not related to the headphone's frequency response. I believe the diaphragm is so heavy that it's causing the attack speed of the driver to suffer in the 800-3000 Hz area. It seems that either titanium wasn't a good metal choice, or they just crammed way too much of it onto the diaphragm...
Oh well, they've still got decay that's competitive way above their price bracket, and they isolate better than anything I've ever used so they're my portables for now. Perhaps a transplant with my series 2 4AAA drivers is in order...
Edited by takato14 - 2/6/14 at 8:33pm