Hmm interesting. After purchase i just immediately swap to the leather pad because many recommend the leather pad for better details and timbre. Will give it a try later.
Edit: tried suede with FT5 it have more air in the vocals but soundstage is smaller than 660s2. FT5 is still the more intimate some might like it, i know someone who love intimate soundstage for more immersion compared to bigger soundstage. 660s2 is wider and deeper in soundstage no matter what song i throw at it. I compare A/B ing it currently. But yes FT5 still have louder bass.
I want to guess regarding our difference in opinion. What amplifier are you using? You know 660s2 is 300ohm right maybe your amplifier is lacking in voltage or is not pairing well with 660s2. While FT5 is easier to drive overall and most amplifier have enough current for it. From all my gear most high impedance gear are quite sensitive to amplification. My Verite is the most picky gear i know of, the sound change a lot just by changing amplifier.
My ZMF perforated leather pads for hd660s2 has arrived will give some time trying the new pads and comeback later.
Tried it.
ZMF perf lambskin Pads: Added a bit of treble (those who hate treble dont buy this pad), reduce mid bass (ouch) while adding a bit of sub bass(im not a basshead but this headphone bass already lacking in quantity. I dont think pads can save it). The sound overall become smoother less grainy. The timbre become more organic . It become more holographic. Soundstage wise i see no improvement it is the same with the OG pad but overall sound become more detailed maybe because of a bit of low to upper treble increase with this pad. Comfort wise this is a better pad it is so soft and comfortable .
When I tried the FT5, 660S2, 650(new pads) and Ananda out in the shop, they were connected to a FIIO K7 and a external DAC (I didn't remember this one).
So all on the same amplifier.
To be honest, I like the HD650 (and probably the 660S2) more on a high impedance source like an OTL tube amp or receiver output. They tend to sound warmer because of the impedance interaction. So my opinion could be different if I would test the 660S2 on a different amplifier. I can think the bass will spread out more evenly on these kinds of amps (but less tight as compromise)
I use a topping L30 at home for my FT5 right now, it's a pretty big update compared to my smartphone/laptop output or high impedance output of my receiver, although the difference I experience is mostly in the bass department or distortion, not the soundstage. The HD650 sounds better on different sources like my marantz receiver and my past OTL.
What I have noticed is that the FT5 is pretty sensitive to how you exactly have them on your head, a little shift can narrow or widen the soundstage quit a lot! Maybe the difference is a bit in the pyshical aspect. Other possibility is that I am pretty sensitive to the characteristics of the treble of the HD660S2, that gives an impact on my experience as whole.
Did you also have experience with the HD650? I found that one wider
With wider I point at the effect it sounds more "around" your head than inside my head. The air between instruments I find a little better on the FT5 but it's not that the HD650 is bad in that aspect.