Eheheh.
Regarding the battery, once again:
- Using "normal" impedance IEM and headphones (16-32 Ohm), single-ended, in SBC/AAC, low gain, normal listening volume, it lasts longer than you can account for;
- Same but with apt-x, expect to lose about less than one hour of battery life;
- Same but with apt-x HD, a little less;
- Same but with LDAC adaptative, some 2 hours less;
- Same but in medium gain, some 3 hours less;
- Same but in high gain/balanced high, some 4 hours less;
- Full sized high impedance (64-150 Ohms) headphones, LDAC/HWA, single-ended high gain (dual-dac, yellow)/balanced high gain (green), be lucky to get 4 hours.
The logical conclusion is that the UP4 offers a very large range of options regarding codecs, gain modes and volume selections, hence some of them will signify a low battery consumption and some of them will require much more battery availability.
Good - no, not good - wonderful news! is that the UP4 is able to power my most hungry full-sized headphones (except the AKG K340, logically - and even this, at full volume, starts to sound almost right, despite its 400 Ohms, a very low sensitivity and its 4 drivers).
Say, if I pick my Sennheiser HD565, at 150 Ohms, and use it in balanced high gain, with apt-x HD, with a good listening volume, the UP4 sounds wonderful, lush mids, a great presence in bass, sweet sweet treble, great dynamics. But I'll be lucky to get more than 3 hours out of it. Same thing for the K701.
If, in many cases, I take my PortaPro or SR60e in medium or low gain, in apt-x, and I usually get more than 7 hours or so. It still sounds fantastic, but it's a different system with different power requirements, hence, different battery life expectancy.
