I see... thanks for all the details.
I use the ES100 with both my iPhone XS Max and my Apple Watch 4, so only AAC is relevant to me. About EQ, being a purist, I like to listen to un-altered music, so I rarely use it. Regarding the BT2, though, I think I’ll pass since it seems it has no benefits over the ES100, other than it can be had for a low price now. The TW1, when it will be re-released, has a major advantage for being true wireless, i.e. no cables, and that’s why I’m eyeing it.
Do the Shure devices (TW1 and BT2) accept dual Bluetooth connections like the ES100 does? Also who’s making the 5K? Where is Qudelix based, in which country?
P.S. Do you use both the SE535 and the SE846? My SE535 have been collecting dust since I’ve got the SE846 in February 2014.