I am about to go on a flight and I was hoping to listen to some music on the way to block out the engine noise, but I want my phone battery to last the whole flight. I have a Mayflower Electronics O2 amp/dac combo that I modded to also include batteries. I would like to use the DAC via my phone because it results in great audio quality, but if it uses more power and drains the battery faster, I will settle to use the 3.5 mm jack with the amp. So does using a USB DAC via USB OTG cable use more of my phone battery than the using the 3.5mm plug on the phone?
If you are using just the DAC, the draw should be fairly minimal. But there will be some power draw. However compared to your normal onboard draw, it might be more. This will depend on what is doing the actual decoding and processing, either the CPU or the DAC.
In a nutshell, you'll have to test it yourself.
thanks for the info, unfortunately I don't have time to test it myself m (I'm not draining my phone battery 3 hrs before takeoff) I was hoping that there was someone out there who has already done this and can share their findings.
here is a helpful website (i hope)
http://www.testusb.com/power_issue.htm
for the headphone, depends entirely on your headphones.