Acix I got the 435S in the other day and I must say the stock pads sound the best. The velors sound bright and bass light and the leather/skin looking ones are too dark for my tastes.
GEAR USED:
Source #1: Onix XCD-99 (Coax Out)
Source #2: COWON S9 32GB
DAC: Music Hall DAC25.2 (Differential Balanced and RCA output)
Amplifier(s): Audio-GD ROC, WA3+ (maxed out, tubes upgraded, Hi-Fi tuning fuse)
The stock pads are much more balanced with the velor ones are more airy and treble oriented, but bass is tighter. Also the soundstage is slightly bigger with those.
The skin ones sound similar to a Sennheiser to me as the treble seems rolled and the bass is more pronounced. Though they sound enclosed and the airiness is cut down a lot. Anther thing is that the soundstage is quite a bit smaller in comparison.
I vastly prefer the stock pads cause they sound much more balanced. Bass is very full and lovely. I guess you can say it has great impact with slower decay. The mids sound somewhat dry to me but are detailed and clear. Treble is the most pronounced frequency spectrum on this phone but not harsh or overbearing. Lots of treble detail and it has decent extension.
SET-UP #1 : NON PORTABLE SETUP.
GEAR USED: Onix XCD-99, MH DAC25.2, Audio-GD ROC/WA3+
Compared to my DT880 600Ohm and HD600, these have a bigger soundstage, theough I think the DT880 has better imaging. The DT880 does have much more midrange presence though and the bass isn't as tight. Also the DT880 has much cleaner treble while IMO the 435S has clearer mids. A comparison between each models bass reveals that the DT880's bass is far more textured and layered while the 435S's bass is tight and focussed. It's kind of hard to describe how it sound.
The HD600 is considered my many a muffled sounding headphone, but I disagree. It's just the treble is rolled off and IMO does not sound muffled at all. The 435S easily has a bigger soundstage than the HD600 by a big margin. The HD600 in comparison has a more congested sound with a more focussed bottom end, though not nearly as tight as the 435S. The hD600 though seems to perform better with a wider range of music than the 435S.
The 435S itself is a great studio phone that is very detailed and also very transparent. But since it's so detailed it will make bad recording or audio files sound much worse. The bass alone is very tight sounding and focussed with decent texture. The bass also has good impact for a studio phone, but nothing compared to the bass of the Denon D2000. Mids are also slightly dry or recessed, similar to that of a DT880 250Ohm IMO, but not the same thing. Though the mids are far more detailed than a D2000 and also more resolving. Treble is very detailed without being harsh or strident. It also seems to extend nicely. Soundstage is actually pretty good on this phone and is bigger then my DT880 and HD600's and that to me is impressive.
I highly recommend amping this headphone since the sound does improve quite a bit.
SET-UP #2 : PORTABLE USE
GEAR USED : COWON S9 32GB
I think the 435S is a great headphone for studio applications, but if you plan on using it with a portable audio player I would not recommend it at all, though I will eat my words and say I'd use it for portable use since it bests my Grado SR-225i's and HD555's. It will magnify the weaknesses in compressed music so much. I found the bass to be slightly bloated when not being amped by a dedicated amp. Also the sound is a little thiner sounding with less detail and soundstage.
