Having used the headphones for about 40 days, there are some conclusions.
I have no complaints about connecting headphones via Type-C cable to PC, they really sound good, amazing. Best solution ever, just for my opinion.
But I got tired of using both USB Bluetooth dongles and my phone also. Perhaps this information will be useful to someone, so I’m writing this.
BTD-800 (Sennheiser-branded) USB dongle delivers good sound (much better than my OPPO phone whule connected via bluetooth), but constantly loses the connection after 10 minutes of inactivity, I have to “dance with a tambourine” several times switching the sound source from headset to my PC (3-4 times back and forth, it doesn’t work on the first switch, lol). In very few cases synchronization with the dongle occurs, but the headphones flies to some crazy "supertransparency" mode like a bug of some kind - I start to hear everything in the room like microphones are working on their full (I move my finger over the earphone from below and hear a strong rustling sound of my finger moving) and this cannot be fixed by turning headset off/on. The mode change button does not help too (it becomes double transparent already being in supertransparent mode with double echo sounding and when returned to "ANC off" I still have undesired supertransparency), there is some kind of hard freeze, only a reset helps. Some kind of a serious software bug on connection level. Sad.
Recently I received
UGREEN USB Bluetooth 5.3 from Aliexpress ($12), the sound quality is worse than BTD-800 and there are occasional small wheezes every 10 seconds. It’s extremely inconvenient to use it on my work machine under Linux according to that noise inserts; I’ll try it under Windows at home when I have enough time for that.
Also I tested it on a cheap Chinese
ORICO BTA-403 USB dongle ($4 lol) - it seems to be stable, although the Bluetooth version is old (4.0). In the output settings, a notification appears that the sound is output through AptX (really?), perhaps this is a fake or they stole the technology? The sound is relatively not bad, although worse than the BTD-800.
Yes, I saw
bt-w5 was noticed as working fine. At the same time, I’m not sure whether this new thing will work on my system differently; after all, the dongle is not cheap and is more expensive than Sennheiser’s.
Perhaps the problem can be in my Linux OS (Linux Mint with Cinnamon desktop) while using USB dongles. In different Linux systems, numerous problems with wireless connections have previously been noticed for many times, this applies to both Bluetooth and Wi-Fi. But I never had any problem using my old PXC-550 headset, for years!
Btw, my co-worker tried to connect IO-12 to his Xiaomi phone via a Type-C <--> Type C cable (on both ends, perhaps in OTG mode?) and it started working with good quality using internal headphone DAC. Unfortunately, this trick did not work on my OPPO phone.
Perhaps I would not have bothered with all that dongles&stuff and used only my OPPO phone as the main source, but... as I told earlier, the sound seems to be kind of flat to me, no wow effect, no drive, no juicy sound, on any eq setting and without it too (comparing after I listened through the BTD-800 and through the Type-C cable from the PC, the overall sound quality is very different on different devices).
I return to the idea that Sony and Samsung were probably and remain the best phones for listening on Android, with the best sound settings, if we consider use via Bluetooth. I experienced the wow effect for years and even danced while walking when I used my PXC 550 with my old Sony Xperia X Mini phone (unfortunately, both are not working as for now), but now there’s only little pleasure in listening, I catch myself thinking that I’m constantly skipping tracks, as if trying find one that sounds brighter than the previous one. So I was convinced that
the presence of AptX codec does not mean that our sound will be rich and powerful on output.
I apologize for possible mistakes in my reply, I don’t know the language very well, but I try not to use a translator but to write on my own