Spent quite a bit of time pad rolling and comparing the non-perforated Ori to the perforated Ori last night (both with the foam insert mod) using the same set of tracks at the same volume to see which was truly superior. In stock form with a couple of hours playtime, they sounded good, but not great pretty much across the board, which is why I got modding immediately. It's worth noting, as I outlined in a previous thread, that these 4XXs also have the grill mod using paper tray mesh and no dust screen along with having over 170 hours worth of play time. They also are using a custom silver-plated 22-gauge OFC cable from Amplifier Surgery. Equipment used in this comparison: straight from my XDP-100R playing the first few tracks from Steve Turre's Woody's Delight (mainly for balance, imaging, sibilance testing) and various tracks from Tame Impala's Currents (mainly for balance and soundstage testing).
Updated Ratings after Ori pad comparison:
4XX (non-perforated Ori + grill mod + foam pad mod): treble 0 / mids -1 / lows +1 / soundstage -1.5 / imaging -1 / detail -1
4XX (perforated Ori + grill mod + foam pad mod): treble +0.25 / mids 0 / lows 0 / soundstage -0.5 / imaging 0 / detail -0.5
I started this comparison because I started feeling as though the perforated pads introduced a touch more treble tipping it into the warning zone for near-harshness. After the comparison though I came to the realization that the recording and volume must have influenced this thinking, as switching back to the non-perforated pads (neutral-dark) they exhibited an almost indistinguishable difference in harshness (which is to say very minimal, again depending on the recording.) The highest brass notes on Woody's Delight inspired only a single wince or two and when it happened it felt appropriate for the recording's intent and intensity.
In this back and forth though I did notice that the non-perforated pads seemed a bit congested which I hadn't noticed without comparing and switching over to the perforated pads the sound opened up with more air/space and better imaging. Jazz recordings can get busy sounding and the perforated pads handled this with ease. The swirling synths on Current's showed the perforated pads to have improved the soundstage to very satisfying levels.
Since I felt that bass was too anemic without the foam pad mod (and previously the hair roller mod), but also slightly too prominent with the foam pad mod and the non-perforated Ori, I was happy to realize that the perforated pads tamed the bass ever so slightly so that a perfect Goldilocks amount of bass tightness/impact/detail/amount was achieved. The juicy distorted synth groove on the tail end of Tame Impala's Let It Happen sent a chill down my body and the upright bass on Woody's Delight had just enough heft and body to seem very real. To briefly explain, the foam (pads or rollers) was used to distance the driver farther from the ears which made a noticeable increase in all things bass and are fit in the ring pocket between the Ori's foam and mounting ring. For a frame of reference, my bass port modded Q701s (think K712 or 7XX) seem to be putting out a similar bass amount (although slightly more body not being as neutral) with the 4XX+Perforated Ori+foam pad mod pulling ahead of the Q701's low end in terms of response, detail, impact, and sub bass.
In going back and forth I also realized just how much more I prefer the modded 4XX over my previously loved Q701s. The soundstage on the AKGs by comparison now makes them seem almost unnatural and odd while the perforated pads and grill mod brought the 4XX to a natural, pleasing soundstage somewhere between the Elear and HD800. Imaging is also quite good and I can easily tell where instruments are in the space. In terms of neutrality, I feel as though the perforated pads improved even further on the non-perforated Ori and am now able to easily focus on whatever instrument I want in the mix without it getting lost or overshadowed. Superb balance indeed. It's worth mentioning that since my previous cans were the Q701, your mileage may vary in terms of treble on this series of 4XX mods although I should say that it is less strident and smoother than the AKGs while never feeling even slightly veiled or losing detail/microdetail.
If you can't tell already, I am loving the 4XXs with this combo of mods and feel as though this might be it for new cans for a while given my high level of satisfaction at this point. Even off of the DAP I was getting goosebumps at the sheer amount of pleasure and technical prowess these things were putting out. There was also a bit of disbelief given how relatively cheap these things were even with the mods ($325 total). So if you have the 4XXs, do yourself a favor and make the same changes. I'm sure you'll be quite impressed as well.