After getting a little more time with the two pads, I did find that the differences were bigger than what I initially heard in the first couple hours of use. Now, I know they seem like they are on their way out, I did want to post something more definitive and final about the pads.
FocusPad vs FocusPad A
As many of you know, there are not one, but two hybrid pads that are available for the HiFiMan HE-series headphones. They are called the FocusPad (production) and FocusPad A (pre-production). The core differences between them visually is that the production pad, on the interior wall, uses perforated pleather. The preproduction model uses velour for the inner wall.
A Word on Comfort
Before I go on to sound, I’ll go over a couple things regarding comfort. The FocusPad A is much more comfortable than the FocusPad. It utilizes a softer foam which compresses easier and reduces the clamping force that the FocusPad has. Also do note that the FocusPad A seals better with my head… That’s my head, so your mileage may vary in that regard. It may also explain the difference in bass I hear.
Starting from the low-end, the bass, as stated does have slight differences to it. The FocusPad A seems to have a little more fluidity to it and less of a body/thump to the low/mid-bass regions. It sounds a lot less one-noted. I’m not sure if this is due to the pad or the seal, but it definitely is evident.
There are two main things that pop up in the midrange for me. The first is vocals. With the production pads, vocals tend to have a bit of raspiness to them, something that the preproduction seems to get rid of. I would not have heard this if I didn’t compare the pads. This doesn’t really bother me though. Some vocals, on the other hand, do gain a bit of air and sweetness to them though. There is a bit more aggression in the midrange which can add a tad bit to detailing with the production. The preproduction pads can be a bit too smooth for me.
There is mainly one thing I hear in the treble, and that’s a bit more softness to it. It’s not as harsh and more forgiving to poor recordings overall with the FocusPad A.
I know a lot of people stated that the FocusPad A were more neutral... I don't think one is more neutral than the other... The FocusPad (production model), graphically, has the peak go back to the "zero" point (@ 1 kHz) in contrast to the rest of the graph if you look at the measurement. Though there is a dip in the 2 kHz... On the other end of things, the FocusPad A is much more linear, though still has a small downslope into the treble (OW-like).
Personally, I find the FocusPad A to be a little too smooth and lacking in aggression shows up for guitars really. The additional treble energy is also very nice. On the flip-side of things, the Focus A (for me anyway) have a much better bass response and fluidity to it. Makes it such a hard choice which pads to use :p I love to rock out, and would love to have both things (aggression and bass fluidity). As of right now, I actually do prefer the FocusPad (production). Though the A is much more comfortable.
Mine with the CrapPad have better bass and HD-800 like soundstage.