The later he-560s were not necessarily lower end, they sound the same imo (I owned the v1 and the v3), but they had come cost saving things like ditching the wood grain because of returns and cost and more importantly they ditched the evil mini smc connectors for the cable. I actually prefer the headband of the v3 to the v1, but it is a preference thing and you can actually buy both from Hifiman directly and swap them out (I did this with my Hifiman HE-6). The HE-560 v4 sucks though, I really hate that style of headband.

I don’t have pics handy, but I own the HE-400, HE-500, HE-560 v3 (v1 is long gone), Arya, and HE-6 (heavily modded now). The HE-6 is by far my favorite, but it is stupidly hard to power properly. They did a remake of the HE-6. but it has that stupid he-560 headband, so you’d have to mod it to make it decent. It also doesn’t sound quite as nice as the OG, but it’s pretty close.

Sorry for the rambling!

I own quite a few of those! I leaned a bit heavier into the higher end of the Beyer and Hifiman lines as I prefer their house sound. Many of those you mentioned won’t do well from any dongle I know of. They “work” technically, but they won’t sound right or loud. The Sonys, Focal, AKG K550, and Phillips X1 are probably OK. It’s odd just how well even the high end Focals do from low power output. The Q701, HD650, DT880-600 and HE-560 are all too demanding for any phone or dongle I have ever used, most DAPs too to be honest. Technically I have the AKG K712 not the Q701, but they are mostly just a tweaked later version of the Q701 with nicer pads.

Only one of my headphones (I own a lot, it’s an expensive rabbit hole) that isn’t a pair of ear buds or IEMs can be powered by a phone or dongle, and I bought that pair specifically because the Nintendo Switch headphone output was super anemic. I have to use a stand alone DAP or stationary amp for everything else.

It can actually be both ways, most USB-C to headphone jack dongles have a tiny DAC/amp circuit built in (they are really tiny and cheap), but there is actually a method for sending audio over USB-C that some phones can use. The latter method is usually fairly device or product line specific, I’m not sure if it is an actual standard or not.

They exist, but they suck (I’ve bought so, so many). Ironically, the best one to use for Android is made by Apple and it still kinda sucks. Not to mention you can’t charge while using them.

You don’t need to even have an appstore installed to make an old phone be a decent DAP. The real issue IMO is that while some of the older Android phones had some decent DACs, but they couldn’t power anything much more demanding than ear buds which any decent DAP can do just fine. Also a DAP battery will last many times longer.

Me too, but only because the fuckers stopped putting jacks on decent phones.