I bought the A105. I'm looking now at the battery, and without playing any music or using the player in any way (just with the display on), the battery is already -1% after 3-5 minutes.
I wanted to try a Sony DAP, and I was deciding between ZX507 and WM1A. I actually ordered the ZX507 from Amazon DE. They didn't ship it in about 3 days. In this time, I thought more how I already tried the M11 Pro which also has Android, and I really didn't like how at times Android was slower, and how the battery life was unsatisfactory.
Eventually, I realized I can easily use the Bluetooth Receiver function of the WM1A to stream music from my smartphone, or the USB DAC mode if I wanted to listen to music from my PC - function which is missing on the ZX507. I also liked the idea of having my own music library as well, and having this device only as a music player, without Wi-Fi capabilites and so on. Also, while on the go you don't have internet anyway. You can share internet from your smartphone, but you can as well stream music via Bluetooth Receiver from your smartphone directly.
So I cancelled the order, and I ordered the WM1A instead. It was one of the best purchase decisions I made in my entire life.
Yeah, maybe ZX507 sounds better while both players are running the stock firmware, but that is due to software, and not due to hardware.
With the custom firmware available for the WM1A, the sound quality is amazing, and I can easily leave the DAP in standby, without having to worry about battery drainage. Of course, there is also the function of auto-shutdown after the DAP was not used for a certain amount of time.
Also, why would I want a DAP that I have to do X and Y tweak in order to get more battery life, as the available one is not really enough?
I understand that I may sound biased, especially regarding the custom firmware, but you can easily check out some opinions from others who tried it as well.
I really hope Sony won't release only Android players from now on.
Peace.