Well I have had this head phone for about a year and some listening to it off and on. My setup is simple. Not hifi, but works. I have an ipod 3rd gen connected to a PA2v2 vis a sendstation LOD connector. I use a Cambridge Audio mini to mini cable to join the two.
I am visiting the UK so decided to do some listening, looking for an upgrade now that I would have the opportunity to listen to a few cans. So I will get straight to it. I will start with the flaws of my DT235.
In my opinion the flaws are a lack of isolation and a cable that is too long. If I nit pick, i could say that it does not fold to be easily transported. Sound wise, its a bit lean on the low end, and the sensitivity is low. Driving it from a portable is fine, but plug in another pair of cans like the Beats, or the Sony ZX600, and the differene in volume is obvious. Otherwise, there is nothing to complain about. So let me do the quick comparisons that I did.
VS the Original Beats by Dr. Dre:
Well I was waiting to do this test now for over a year, but never got the opportunity. Well the has come. My brief sessions told me this. The Beats are bass heavy, and to my ears, unnatural in the midrange, sounding too rich I presume from bass bleed into the lower mids. The treble also lacked the sparkle that I am accustomed to. The Beats are LOUD. They can be easily pushed by a portable source, but the sound just was not my cup of tea. I easily preferred the Beyers. They sounded more natural, more organised, with good treble extension, a clear midrange and a good overall balance.
VS the K451
These I heard briefly as well and left preferring the Beyers. They sounded good, with a hard hitting bass line nd nice mids, but seemed to have a muted treble which made the music sound slightly muffled. I will listen aagain, but from that short listen, I saw no reason to consider it an upgrade.
Vs the Sony ZX600.
This is a good headphone. The sonic signature of the Sony compared to the Beyers is lack of refinement. The bass is more driving and aggressive. the highs are not as crisp, but have similar extension. The sound is good, but it feels a bit messy. Overall though, it is enjoyable.
I did test a few other headphones from Philips and Denon and Sennheiser, and left with the conclusion that if you don,t mind the lack of volume, and can live with the lack of isolation, there is definitely alot to love about the Beyer DT235. From my brief listening sessions, it punches above its weight in terms of sound quality. and having to travel in my backpack with alot of other junk squeezing it and compressing it, it shows durability. It may not have the bass kick or the sonic excitement of some others, but its balanced and refined sound makes up for its small lack of dynamics.
The long and short of it. It has impressed me to no end and I am not sure if there is really an upgrade for it under $US100. Surely underestimated in my book. and worth the the US$ 50 I paid for it.