Those are both battery powered portable amp/DACs. Different products than the dongles. The battery powered portable amp/DACs can have more powerful headphone amps in them because they're not limited by the power from a USB-C port from a portable phone. They can be more powerful and potentially sound better and won't drain the phone's battery as much. But also means you have to keep them charged and they're also big things that are heavy and inconvenient to carry around with your phone.
No, I got mine through AT&T. Never had any problems so I can't say anything about a bootloop. The sound quality with a dongle DAC is pretty good. I'm not sure if I would invest any time or effort into trying to repair my V10 if anything went wrong.
So like 2V...not much more. 600 ohms doesn't need much current but it does need voltage. I'd think some kind of DC-DC conversion could generate more but maybe it takes too much space? Or cost? Or nobody but me and a few other nuts care? I have Monolith by Monoprice USB DAC - Monoprice.com (only $59 now!) kindly gifted by a friend. It sounds a bit different from my MacBook Air output but subtle-surely in part because I can't get very loud with either. Generally I don't bother to use it. Perhaps I should write some letters to Monoprice, AudioQuest, et all asking "can't you make a high voltage version?" Hmmm...maybe they don't because with lower impedance headphones the current output would just choke out into clipping. Maybe I'll write and ask them to make a USB tube headphone amp, with miniature tubes, THAT would be cool. Use more power...but hey out of USB-C couldn't you make a Power Delivery dongle and get a bunch of power? I suppose the output on laptops and especially phones aren't set up for that. Really instead of lugging around clunky stuff with your phone, one might be better off searching out headphones that are synergistic with the phone's output.
I don't carry around expensive headphones/earbuds on the go as I mainly use my B&O earbuds that came with my LG V20. It sounds good for what it's worth. I wish but the number of smartphone users who care about audio quality is quite minuscule in the grand scheme of things. Plus, almost no new smartphones come with a 3.5mm headphone jack so it's either buy wireless Bluetooth headphones/buds or buy an aforementioned adapter.
There are balanced dongles that can do 4Vrms output. That's an advantage due to the balanced amp designs. Astell & Kern just announced a balanced dongle that does 4Vrms. They already have a single-ended dongle that does 2Vrms. And their single-ended one is getting a firmware update so it will be supported by their new Android app. PEE51 single ended: https://www.moon-audio.com/astell-kern-usb-c-dual-dac-cable-pee51.html PEE52 balanced: HC2 USB-C Dual DAC Cable (PEE52) It's A&K so not cheap. HeadFi announcement: Astell&Kern to Debut Three New Products at High End Munich 2022 So for phone compatible headphone DACs we've got USB-C dongles. And if you need more power then you've got the portable battery powered amp/DAC options from companies like Fiio and iFi like the iFi xDSD Gryphon ($599).
For those who want a mint- V series phone (or any used phone) at a good price, I recommend swappa.com. They verify all IMEI / ESN numbers and are much pickier with their sellers than Amazon or ebay. Inexpensive also.
After 2 years you're probably not getting any major Android updates anyway, so after three years you should probably switch to a newer phone.
The Xperia's DAC isn't anywhere near as accurate as those from ESS (compare with the ROG Phone 5 below). It also has an unfortunately high output impedance: DAP TI Database, HypetheSonics The ROG Phone 5 looks like it's still king: DAP TI Database, HypetheSonics The sad thing is this is a couple of years old now. Strange that nobody else is making phones with quality DACs built in, because those ESS chips aren't that expensive.
