| It seems that recent Linux kernels (4.8 or 4.9) have support for the Line 6 Pod X3 (http://line6.com/legacy/podx3/).  I had found a better reference, which I can't find now, but see this: http://cateee.net/lkddb/web-lkddb/SND_USB_PODHD.html 
 It seems that it is recognized: puslseaudio (pavucontrol) shows it, although I cannot get sound of it.  (The meter does move when I play, though.)
 
 Here is some info:
 
 
       Code: 
# lsusb
 Bus 002 Device 002: ID 8087:8000 Intel Corp.
 Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 001 Device 002: ID 8087:8008 Intel Corp.
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 004 Device 002: ID 174c:3074 ASMedia Technology Inc. ASM1074 SuperSpeed hub
 Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 003 Device 006: ID 046d:c52f Logitech, Inc. Unifying Receiver
 Bus 003 Device 005: ID 046d:c517 Logitech, Inc. LX710 Cordless Desktop Laser
 Bus 003 Device 003: ID 0846:9030 NetGear, Inc. WNA1100 Wireless-N 150 [Atheros AR9271]
 Bus 003 Device 012: ID 0e41:414a Line6, Inc.
 Bus 003 Device 002: ID 174c:2074 ASMedia Technology Inc. ASM1074 High-Speed hub
 Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 
 
 
       Code: 
# lsmod | grep pod
 snd_usb_podhd           3865  0
 snd_usb_line6          21723  3 snd_usb_podhd
 snd                    56967  23 snd_oxygen_lib,snd_oxygen,snd_hwdep,snd_seq,snd_hda_codec,snd_usb_audio,snd_timer,snd_mpu401_uart,snd_rawmidi,snd_usb_podhd,snd_usb_line6,snd_usbmidi_lib,snd_seq_device,snd_pcm
 usbcore               165880  13 ath9k_htc,usbhid,snd_usb_audio,usb_storage,ehci_hcd,cdc_acm,snd_usb_podhd,snd_usb_line6,xhci_pci,snd_usbmidi_lib,uas,xhci_hcd,ehci_pci
 
 
 But, I cannot connect it thought jack...  Here are the errors for two attempts to start jack with the X3 as input:
 
 
       Code: 
01:10:44.298 Statistics reset.
 01:10:44.304 ALSA connection change.
 Cannot connect to server socket err = No such file or directory
 Cannot connect to server request channel
 jack server is not running or cannot be started
 JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for 4294967295, skipping unlock
 JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for 4294967295, skipping unlock
 01:10:44.395 ALSA connection graph change.
 01:11:07.248 JACK is starting...
 01:11:07.249 /usr/bin/jackd -dalsa -r48000 -p1024 -n3 -D -Chw:PODX3,0 -Phw:DGX,0
 Cannot connect to server socket err = No such file or directory
 Cannot connect to server request channel
 jack server is not running or cannot be started
 JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for 4294967295, skipping unlock
 JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for 4294967295, skipping unlock
 no message buffer overruns
 no message buffer overruns
 01:11:07.264 JACK was started with PID=19919.
 no message buffer overruns
 jackdmp 1.9.11
 Copyright 2001-2005 Paul Davis and others.
 Copyright 2004-2014 Grame.
 jackdmp comes with ABSOLUTELY NO WARRANTY
 This is free software, and you are welcome to redistribute it
 under certain conditions; see the file COPYING for details
 JACK server starting in realtime mode with priority 10
 self-connect-mode is "Don't restrict self connect requests"
 audio_reservation_init
 Acquire audio card Audio1
 Acquire audio card Audio0
 creating alsa driver ... hw:DGX,0|hw:PODX3,0|1024|3|48000|0|0|nomon|swmeter|-|32bit
 configuring for 48000Hz, period = 1024 frames (21.3 ms), buffer = 3 periods
 ALSA: final selected sample format for capture: 24bit little-endian in 3bytes format
 ALSA: cannot set period size to 1024 frames for capture
 ALSA: cannot configure capture channel
 Cannot initialize driver
 JackServer::Open failed with -1
 Failed to open server
 01:11:07.328 JACK was stopped
 01:11:09.379 Could not connect to JACK server as client. - Overall operation failed. - Unable to connect to server. Please check the messages window for more info.
 Cannot connect to server socket err = No such file or directory
 Cannot connect to server request channel
 jack server is not running or cannot be started
 JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for 4294967295, skipping unlock
 JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for 4294967295, skipping unlock
 01:11:38.772 JACK is starting...
 01:11:38.772 /usr/bin/jackd -dalsa -r48000 -p1024 -n3 -D -Chw:PODX3 -Phw:DGX
 Cannot connect to server socket err = No such file or directory
 Cannot connect to server request channel
 jack server is not running or cannot be started
 JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for 4294967295, skipping unlock
 JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for 4294967295, skipping unlock
 no message buffer overruns
 01:11:38.784 JACK was started with PID=19932.
 no message buffer overruns
 no message buffer overruns
 jackdmp 1.9.11
 Copyright 2001-2005 Paul Davis and others.
 Copyright 2004-2014 Grame.
 jackdmp comes with ABSOLUTELY NO WARRANTY
 This is free software, and you are welcome to redistribute it
 under certain conditions; see the file COPYING for details
 JACK server starting in realtime mode with priority 10
 self-connect-mode is "Don't restrict self connect requests"
 audio_reservation_init
 Acquire audio card Audio1
 Acquire audio card Audio0
 creating alsa driver ... hw:DGX|hw:PODX3|1024|3|48000|0|0|nomon|swmeter|-|32bit
 configuring for 48000Hz, period = 1024 frames (21.3 ms), buffer = 3 periods
 ALSA: final selected sample format for capture: 24bit little-endian in 3bytes format
 ALSA: cannot set period size to 1024 frames for capture
 ALSA: cannot configure capture channel
 Cannot initialize driver
 JackServer::Open failed with -1
 Failed to open server
 01:11:38.845 JACK was stopped
 01:11:40.970 Could not connect to JACK server as client. - Overall operation failed. - Unable to connect to server. Please check the messages window for more info.
 Cannot connect to server socket err = No such file or directory
 Cannot connect to server request channel
 jack server is not running or cannot be started
 JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for 4294967295, skipping unlock
 JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for 4294967295, skipping unlock
 
 
 Is there any thing that must be done to get it to work?  (I assume the the aptosid kernel does support it, right?)
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