Thanks very much for reading and for the kind words!
You shouldn’t have any trouble powering an 80 ohm DT770 out of a smartphone…though they won’t get as loud as the M50X’s would. I’ve even used my 250 ohm 770’s out of my phone before, though I have to crank it up to about 3/4’s of max volume to have a comfy listening experience.
I don’t tend to really crank volume, and Beyer’s headphones tend to be a little less sensitive, and thus softer, than competing models.
The only problem I can think you might have with a phone and the 80 ohm version is the 10-foot, non removable cable. The 10-foot cable is fine if you’re sitting at a desk or table…but if you’re ever planning on walking around with the phone in your pocket, it’s going to be a bit of a rough experience.
Consider these other two options:
1- The Beyerdynamic DT770 Pro 32ohm version. It has a shorter, pocket-friendly cable and leatherette ear pads that isolate even more. It also has an impedance that’ll allow it to get a little louder out of a phone.
2- The Beyerdynamic Custom One Pro Plus. These have a slightly different sound to them…but come with a removable cable. One of the included cables even has a phone remote and mic built in. And there’s lots of fun customization features as well.
I’d have a better time using those two with a phone than I would have with the 80 ohm DT770, but those are just my personal preferences!
If you liked the sound of the M50X, I think you’ll like the sound of the 770 as well! They’re definitely close cousins, sound signature-wise.
Thanks again for reading and for the question.