Saoshyant
Headphoneus Supremus
Yep, battery not rapidly depleting on my smartphone, and was able to run through the Q1 mkII internal battery and need to charge it. Also, that same ebay seller has this: https://www.ebay.com/itm/10cm-Right...TG-Cable-4-DAC-Digital-Amplifier/301669713346 which seems to be what you need. Fingers crossed it also lacks the ability to charge.
Mine just arrived, and can confirm no draining of battery using this cable, but it doesn't like to stay in my LG G6, so unfortunately I cannot use it with this phone. I recently picked up an inexpensive iPhone SE, so I'll probably just stick with this for out and about listening.