Good to know its doable. Like you though, no plans of ever taking it out

Have you tried taking out your Hart cable? Not able to get mine out as easily as the stock ones

Out of all the headphones I have (6xx, r70x, clear og, arya) the HD800s has noticeably the widest soundstage with nearly the best imaging as well (the Arya Stealth's are slightly better). As for cheaper options, I believe that the AKG K702 or K712 comes close in soundstage width but may be lacking in other areas. Idk if Arya's really complement the HD800S well, they both sound similar except Arya's have more bass. If you want HD800S for just music, I'd pass if you already have the Arya's. If you want them for gaming/movies, I'd say it's worth considering.

Does the LCD-X sound best when EQ'd to be that dark as in wouldn't it drown out the mids? If the bass is different enough from the Arya's/Clears than it might still be worth looking at - especially since it can be EQ'd real low at 20hz which the other three can't do well.

Cannot agree with you more about the Clears. Amazing for most of the music I listen to, but way too intimate of a soundstage for gaming/movies (where voices sound a little unnatural). It's a screaming good value though, and I actually prefer it without any EQ (except some moderate bass boost). I use mine to focus/study as their metallic timbre is perfect for more melodic/instrumental music.

I was iffy about sticker modding an HD8XX so I got the HD800S instead, but its awesome that you've had success with it. I also agree with your analysis of HD8xx/Arya except I have the Stealth which is supposedly less bright than the V2 (but V2's have more soundstage). My Arya's are my go-to pair for enjoying music, everything sounds amazing on them (but I do miss the dynamic-ness of the Clears here sometimes). I haven't really figured out how to get the most of my HD800S for music yet, but it gets probably the most usage out of all my headphones as I use it for gaming/movies. The soundstage is just wayyy too good. If I had to pick one though, I'd probably pick the Arya's since they're an exceptional all-arounder.

Man, I really wanted to round out my kilobuck collection with the LCD-X but after reading your post, I'm having second thoughts. Might just go for the HEDDphone or a ZMF instead. Out of the other three, which one have you been enjoying the most?

I'm not too sure about the effects on soundstage as I've never used anything other than stock pads myself. I know that the HD800S has a dead-zone where the soundstage is perceptibly wider, so that may be something to consider with 3rd-party pads as they might alter that angle. Don't take my word for it though.

As for tightness, is your headband adjustment all the way in (the tightest setting)?

The clamp force is too tight but you want ear pads that make it even tighter? The consensus from previous reddit threads is that 3rd party HD800s pads will alter the sound negatively. If you're open to EQ, then the Dekoni fenestrated pads might be a good choice (see here). My HD800S never gets sweaty with stock pads since they're so roomy, but I imagine the fenestrated might after a couple of hours.

People are saying burn in doesn't exist, but in my experience it definitely does, whether it be the drivers themselves or my brain from getting used to the sound for a while. Give it some proper listening time and then re-evaluate.

As for amps, I don't subscribe to buying amps for the sound (as you can see, I'm happy with just a Schiit Magni). I think you're probably fine with the amp you have as long as you're able to listen to it distortion-free at the volume that you like. Is there a reason you went for the Diana without auditioning them first? I, personally, can't trust any Abyss products when they're peddling $2k cables and $2k aluminum racks.

Did you audition them somewhere first? Did you let them burn in? Never heard them (and never plan to) but from what I remember, Josh Valour said it was fairly amp picky in that it emphasizes the amp's sound qualities.

Stock tips - the smallest silicone ones.