Yesterday, I could use the Stealth in 4hours time trains and basically Isolation is rather consistent, so it makes possible to enjoy a high SQ though a high ambient noise without being obliged to push the volume to a dangerous sound pressure for the ears. I got some discomfort after a rather long time keeping the Stealth on my head, but not worse than my Sony Z7M2, Ultrasone Ed15 Veritas or even HEDDphone One(at home). My ears don't touch any parts of the pads (like Ultrasone Ed15) or somtimes the cups (like my Z7M2). Weight is definitely not an issue (but the 700g of the HEDDphone one is not an issue either for me).
I tried also some other chifi portable amps like Xduoo XD-05+ (2x1W@32ohms SE), Hifi MQ1S(2W@32ohms Balanced) and none could provide a clean sound on most low and ultra low frequencies in a track from Max Richter "Cradle To The Grave" like the M8V2 can't do too (Of Course Sony WM1A, Fiio M11 and A&K Kann Alpha can't manage to offer clean low frequencies too in many other cases).
Till now, the only portable amp which managed to be clean and powerful enough (when needed with some DSD in bit perfect mode) on all tracks is the Less BX2+ (2x3W @32ohms). I have still some hopes with Fiio M17 or Ampersand before Christmas to be powerful enough and still with a decent battery life with the Stealth
I would say, it's the first time I can use a headphone which doesn't need any EQ and can be used everywhere I want with a top end SQ !!!!
The A&K Kann Alpha manage to be usable most of the time at a comfortable sound level, but it is lost when power is really needed (clipping, hisses and distortion). The Less BX2+ has almost no fail in any situations, but it is definitely bulky, not attractive at all, with a really short battery life (3hours with the Stealth), but can be plugged to an external power bank like Samsung EB-U3300 10000mha while playing.
It's pity, but I have no mind to try the WOO WA11, as I still doubt it has a real chance to be powerful enough like the BX2+ is, and probably, in such small box, the battery life must be rather anorexic too when drained by a DCA Stealth.
It's less than one week I am using the DCA Stealth (more or less 15 hours) ... I am already nearly sure it's a keeper, though it seems to be overpriced, but it will probably replace my Ultrasone Ed15 Veritas though it's bulkier, heavier, hard to drive on the way (but not impossible). The Stealth has a really high SQ without any EQ and it is still a real closed headphone which is compatible with using it on the way (Planes, Trains, Hotel) or at home when we are not alone in a living room. There is probably no alternative on the market that can be as versatile as the DCA Stealth in such a range of SQ. That's pity, it's a 4100€ ticket to acquire such toy (though it's not worse than acquiring a good bicycle, a motorbike, a quad bike, a jet-ski, aski-doo, an 8K Oled TV, etc etc ....)