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USB DAC in use, but still shows "speaker" as output


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Do only certain DACs get "recognized" by Poweramp?

I have a pair of Nexus 7 2013 tablets (Stock android 6.0.1 and LineageOS Android 7.1.2) with a SoundBlaster E5 DAC with OTG support. As soon as I plug it in, the audio comes out of the DAC (and not the built in speaker), but the app still reports the "Speaker" as the output and it is still downsampling to 16bit and rate. The same behavior is present even if the tablet is rebooted with the DAC attached.



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My issue was related to using the "USB host" port on the SoundBlaster E5. Works great with the OTG cable plugged into the micro USB port from the stock firmware Nexus 7 (not from the LineageOS one though).

Micro USB is preferable to the USB Host as it allows you to disable "charging" between the batteries of the two devices.

One down side to Micro USB connection is the seemingly unconnected DVC (two volume controls, one on unit and in system). With "Host" cable, an adjustment on the device indicated a volume change on the phone (implying DVC).

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@chaseadam Thanks for the report. On Android 5-7 there is no open and reliable API to query the currently active output. Also number of active outputs is not limited to just one, some devices can play to multiple devices at the same time. There is kind-of-is some APs but it's broken, i.e. it lies about output depending on the Android/OEM/etc. There are few newer APIs for the Androids 8+ which work better, but on 5-7 Android some complicated logic is used to detect output and it may fail as in your case. I will try to reproduce the issue on the similar device though.

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more details from the E5 user manual:


Phone / tablet running Android 4.1 or higher for USB Host Audio Streaming*

* Devices firmware must implement AOA2 protocol that support USB Host Audio Streaming

Looks like audio support was limited to specific bit/sample rates is deprecated per https://source.android.com/devices/accessories/aoa2 so no good reason to dig into this more:


Caution: AOAv2 audio support has been deprecated in Android 8.0.

AOAv2 includes support for audio output from an Android device to an accessory via a standard USB audio class interface capable of 2 channel, 16-bit PCM audio with a bit rate of 44100 Khz (additional audio modes may be added in the future).



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