I didn't like the Fostex TH900mk2 as much as I thought I would. I listened to them on a silver dragon cable at Moon Audio's table.
I'd honestly have to take the Stellia over them.
I don't think the Stellia really lacks anything. It's one of the (not the only) most perfect headphones I've ever listened to. I liked it better than the Utopia and other more expensive headphones.
Again though, when you can get the Elegias plus the Dekoni limited edition Stellia pads, you're getting maybe 50-75% of what you get from the Stellias...so are the Stellias 6x better? Because that's the price jump. They're a luxury. I'll get them one day for sure, but not before getting a variety of other headphones.
For more bass, the deep and lush bass, I'd probably look at ZMF. I think one of the biggest differences between Focal and ZMF being that to my ears Focal is more dynamic and energetic. ZMF is more smooth. That isn't to say Focal is fatiguing. For as being as dynamic and visceral as they are, they manage not to get fatiguing. You might otherwise think ok one or two songs is enough. Somehow Focal manage to stay on my head for a good while.
These Meze 109 Pros though (listening as I'm typing here on my phone). They're just reminding me so much of the Nightowls in terms of comfort/fit and sit somewhere between that laid back smooth sound and the Focal dynamic energy. I'm still forming impressions though. I know, not closed back, sorry. They are beryllium coated though, but Stellia has slightly more detail and speed. Less soundstage though given they are closed.
After a few months with the Stellias I think the same, but dependend with the genre or kind of music I listened more and more to the Hifiman XS. I did not expect that. Sometimes I like more to listen with that 500 euro headphone than with a 3000 euro headphone. I bought the XS more or less for movies, Youtube Videos and if I really want the open headphone feeling and more comfort. Because I like the XS so much, I bought the Hifiman Arya and this hp has other advantages to the Stellias like the immersive, open music listening in comparision and is really fast and crystal clear. Hard to compare, because the Stellia and the Arya are totally different.
I had the Elegia plus the Dekoni Stellia pads and compared them side by side with my Stellias. The Elegias should be my "portable" hp outside, at traveling.... I'm sorry to say, but this combination had nothing to do for me with the Stellias. The tuning is completely different. Could be that you get 50-75% in terms of details, but the tuning is different and the whole sound experience. The Elegia had a good amount of details, but in comparision with the Stellias they sounded totally dead. With the pads they sounded dead with more bass. Like dead neutral. Even if they are not neutral per definition. They are far far away of "fun headphones" especially with modern genres.
I kept the Dekoni Stellia pads for the Clears OG for a little bass boost, but I'm listening to the OGs with the original pads, because they give them more clarity (treble).
I think the Meze 109 Pros could be really interesting, but I can't justify another headphone. Probably if the TH900mk2 aren't my thing.
Agreed that there is no perfect headphone, better luck catching a dragon

.
I have not heard the stellia or the th900mk2. I've always wanted to try both of them but never got the opportunity and didn't want to buy blind.
I have the Focal Clears and upgraded the driver wires to 18awg mundorf silver gold and resoldered everything with mundorf supreme as well as change the pads to custom leather pads. They have excellent bass impact but doesn't extend well, tapers off in the sub bass region. As much as I enjoy them, I need closed backs due to others in the household.
I found the aryas had great quality to the bass but lacking in the impact and volume to satisfy the itch for me.
I recently purchased the TRN Kirin which is a planar iem and it has reinvigorated my interest in planars, the speed is quite addictive and while the clears are quite fast for a dynamic, I find that it still can't match the speed of the planar.
This is why I'm very interested in the Sundara closed back.
I can understand the need for a closed back. I enjoy my Clears, too, but its not enough bass, especially for modern genres. The sundara closed back is really interesting, because they should have a lot of impact and speed. The Hifiman Arya is very good for modern genres, too, especially EDM. The TRN Kirin sounds interesting, too. The planar IEM Supermoon from Campfire Audio should have the same properties (fast+good bass). I tried the U12T, I really like this IEM a lot, but they are a little bit too relaxed and I miss the impact/DD Bass.
You'd probably like the Stellia. I loved the Clear MG I tried but ultimately I passed on it because I have the Focal house sound in my collection. So you'd be presented with the same thing I'd imagine. Double down on that sound signature? Or try something else?
I think ZMF may reach deeper. Definitely try the Stellia and some ZMF if you can. If you're after the speed, the Stellia may be fast enough for you. I was a huge planar fan, but the dynamic drivers are getting so good now that I think they're just barely losing out here in terms of speed with some of the newer stuff that's coming out.
I think the same, that you can't go wrong with the Stellias. In Europe you can get them for 2000 EUR. I posted my impression with other closed backs in another thread:
Meze Liric: boring and overpriced for its technical abilities. In Europe you can get the Liric at the same price as the Stellia, so thats the benchmark. Perfect comfort.
DCA 2 closed: sounds like an open one (but I like the intimate sound of a closed one), very neutral and sounds compressed. Perfect comfort.
Focal Elegia: sounds dead neutral, even with the Stellia pads and a little bit hollow.
Focal Clear MG: I thought the bass would be nice and it is, but unfortunately it's much too dark and I missed the brilliance of the OG (treble)
Focal Clear OG: perfect all-rounder, everything just sounds good, very nice bass and treble. For 850 Euro its a steal.
Focal Stellia: Technically impressive, which makes a lot of fun. No easy listening, can be exhausting.
Focal Radiance: Sounds really nice, but in comparison with the Stellia a little bit boring, but relaxed. The bass is really nice. I thought about keeping it to complement the Stellia, but wanted a completely different sound signature and something fun and exciting. With one word I would describe the radiance with "relaxed".
Had no experience with ZMF, because these are in europe really expensive (VC closed is at 2750 euro)