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Do you mean 2.1 mode won't work with all usb audio since surround 5.1

of usb audio is already using route plugin

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What do you mean by "all usb audio"? In 4.1/5.1 mode LFE and all other

outputs work properly, it is just for 2.1, which works as stereo.

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If you don't have SPDIF output/input, you need to add your card in

USB-AUDIO.conf

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Sound card has S/PDIF output, but not input. Not sure whether output

works properly though. I do not have speakers or any other hardware with S/PDIF input to test it.

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In 2.1 mode LFE is not actually working at all, so it is removed.

Do you mean 2.1 mode won't work with all usb audio since surround 5.1

of usb audio is already using route plugin

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USB-Audio.pcm.surround51.0 { @args [ CARD ] @args.CARD { type string } @func refer name { @func concat strings [ "cards.USB-Audio." { @func card_name card $CARD } ".pcm.surround51:CARD=" $CARD ] } default { type route ttable.0.0 1 ttable.1.1 1 ttable.2.4 1 ttable.3.5 1 ttable.4.2 1 ttable.5.3 1 slave { pcm { type hw card $CARD device 0 } channels 6 } } }

http://git.alsa-project.org/?p=alsa-lib.git;a=blob_plain;f=src/conf/pcm/surr...

type route slave.pcm { @func refer name { @func concat strings [ "cards." { @func card_driver card $CARD } ".pcm.surround51." $DEV ":CARD=" $CARD ] } } ttable.0.FL 1 ttable.1.FR 1 ttable.2.LFE 1 hint { description "2.1 Surround output to Front and Subwoofer speakers" device $DEV }

2.1 seem use 5.1 and route plugin

If you mean route plugin cannot be used twice, you need to remove surround 2.1 from USB-Audio.conf