Hey, Ultra, aside from that one particular track you mentioned earlier (unless it's the best example), do you have a track that really highlights the grainy mids on the OPPOs for you? I'd like to see if I can hear what you're referring to compared to my HD650. My tracks might not be highlighting that area, as I hear most everything as smoother on the PMx2. Might also just be me listening for something different or not being sensitive to things you may be.

Try Talking Heads Unfinished Outtake 1:43 to 1:54 (synthetic keyboard):

https://play.spotify.com/track/6CtUsDcTVu2JYbZevtaiQ5

To me it sound edgier and grainier on the PMx2s than the HD600s (not sure about the HD650s because that's not what I have with me at the moment.)

Then try Talking Heads  This Must Be The Place (start). It also sounds edgier and grainier to me on the PMx2s. Move on to 1:28 to 1:40 on the same track. I felt a loss in resolution and things sound as if about to clip.

https://play.spotify.com/track/6aBUnkXuCEQQHAlTokv9or

Bass is awesome. But IMO there are better out there.

I know the OPPOs are relatively insensitive to seal (personally, I feel they're less sensitive to placement than they are less sensitive to seal), and I'd like to move away from the measurement rig discussion, but I would be curious to see what results you get from a less leaky baffle/coupler for shits and giggles.

Leaky vs Non Leaky measurement:



There are differences between the measurements due to coupler. But they are not nite and day as in some other cans. Specially in the bass where some cans will go limp dick in the absence of proper seal.
 

I do not think measurements of the very same headphone on different (DIY) rigs should be expected to look exactly the same. There are simply too many variables that have an effect. I guess what makes more sense is comparing measurements of different headphones or modifications on the same rig and drawing conclusions based on differences and similarities.
I find my humble rig useful because it of gives me "objective" feedback for what I am hearing when performing modifications. And, with some experience, I have found that by simply looking at a frequency response/distortion/CSD plot resulting from a modification I have a very good idea if the mod will sound good or not. Very often I mod the headphones until I achieve such a promising-looking graph (on my rig) and then listen. Almost always a nice looking graph corresponds with good sonic performance. But finally it is your ears that provide the final verdict.
And, I am very much certain that my headphones will measure differently on a different rig. At least to some extent.

Certainly. However, that is not what I think Alex finds objectionable about my measurements. His measurements show this delta in improvement (and no channel imbalance at all) vs Oppo cans ("crap" Oppo cans above, "Alex-Awesome" mod below):



My measurements show this delta:



Obviously his delta improvement and mine do not match. Perhaps I measured a stock PM1 and PM2 as baseline, and Alex started with a broken PM2 set. Alex claims in so many words that my rig is broken and his measurements from his super-secret rig and bat-like hearing tells him his cans are uber-netural and worth well over $1k. Any disagreement will yield a "Sorry, you're wrong", "don't understand why", and in so many words, ears in disagreement are not discerning.

Well, my un-discerning ears tell me his cans are just OK, but not amazeballs. I feel that simpleton HD600s are superior to his cans.

As far as looks, I also prefer the stock Oppo presentation to this:

Please provide a comparo of your measurements of stock vs modded Hans.

FWIW, the cans that Alex modded and sent to me in the past sounded and measured MUCH WORSE than stock cans.

And while my methods are far from perfect, subjectively the cans sound noticeably different to my ears. Still in the same vein, but noticeably different in some relatively large ways (not talking like going from a Senn to an Ultrasone, of course)

The measurements that Alex provided indicate that the modded cans would not be even in the same vein.

Well, my un-discerning ears tell me his cans are just OK, but not amazeballs. I feel that simpleton HD600s are superior to his cans.

hello,

this is going to get interesting.

If it's ok by Alex, I could put the set he sent me on tour after OJ and I have made comparos w the Mad Dogs + 600 + Slants this next week...