TH-900 was quite a nice surprise as it managed to be considerably better than the old Denon D7000. The review got me through a very nice audio journey and they proved to be a fun and worthy companion.
Their bass section is impressive on some songs and music genres and I think that they have the strongest sub-bass I’ve heard until now. Fostex managed to do this without bleeding into the midrange.
However, combined with a recessed midrange and peaky treble, TH-900 offers a colorful sound that can be quite enjoyable on some songs, but distract your attention on others because of a too powerful bass or piercing treble.
The soundstage on TH-900 is another important plus that Fostex managed to bring to the table. Even if they are closed headphones, their soundstage was in the league with some open ones.
TH-900 doesn’t have a strong isolation, so if you need that, they might not be the best choice for you as they leak sound almost like open headphones. However, they isolate a little bit, and this helps in getting a blacker background.
I would have loved them even more if not for the recessed midrange and sometimes piercing treble. If you like rock music, they might not be the best solution as the cymbals were painfully screechy in my opinion.
I think that overall, they might be the best closed headphones I have tested until now.
Considering that the price has lowered considerably, I recommend these headphones, especially if you like electronic music and heavy bass.
Pros
King of sub bass with good bass that goes deep but manages to keep control packs a good punch
Very good soundstage, instrument separation and imaging
Good transients with strong attack and fast decay
Good viscerality on some instruments, especially guitar strings
Good amount of details
Black background
Appealing design and looks
Good build quality
Cons
The bass is sometimes too much and distracts you from the rest of the spectrum, also gets tiresome after a while on some songs
The treble is sometimes more piercing than on HD800
Recessed midrange that puts the voices and instruments in the back (with the exception of some guitar string plucks)
Non detachable cable