> Yes, the discussion has ended without real solution. So this is why I've 
> asked here again.
> As soon as the China device arrives I can test if it has the same issues like 
> your Schiit.

OK, device has arrived:
lsusb:
Bus 007 Device 003: ID 0d8c:0309 C-Media Electronics, Inc.

lsusb.py:
 7-3            0d8c:0309 ef  2.00   12MBit/s 100mA 3IFs (CMEDIA USB2.0 
High-Speed True HD Audio)

/var/log/messages:
Dec 11 19:48:44 pinkfloyd kernel: [  853.775100] usb 7-3: new full-speed USB 
device number 3 using ohci_hcd
Dec 11 19:48:44 pinkfloyd kernel: [  853.915155] usb 7-3: not running at top 
speed; connect to a high speed hub
Dec 11 19:48:44 pinkfloyd kernel: [  853.934143] usb 7-3: New USB device found, 
idVendor=0d8c, idProduct=0309
Dec 11 19:48:44 pinkfloyd kernel: [  853.934154] usb 7-3: New USB device 
strings: Mfr=1, Product=2, SerialNumber=0
Dec 11 19:48:44 pinkfloyd kernel: [  853.934161] usb 7-3: Product: USB2.0 
High-Speed True HD Audio
Dec 11 19:48:44 pinkfloyd kernel: [  853.934167] usb 7-3: Manufacturer: CMEDIA
Dec 11 19:48:44 pinkfloyd kernel: [  854.001318] input: CMEDIA USB2.0 
High-Speed True HD Audio as 
/devices/pci0000:00/0000:00:16.0/usb7/7-3/7-3:1.2/input/input8
Dec 11 19:48:44 pinkfloyd kernel: [  854.001694] generic-usb 
0003:0D8C:0309.0006: input,hidraw2: USB HID v1.00 Device [CMEDIA USB2.0 
High-Speed True HD Audio] on usb-0000:00:16.0-3/input2

What I've done so far:
The device only has digital outputs. I've connected it to my AVR via optical 
link. For tests I'm using Audacious (output set to hw:2,0; bit depth 32 bit as 
suggested). The system is running Slackware 14.0 with kernel 3.2.29 (Alsa 
1.0.24).

Problems:
* There is a blob when playback starts
* 12MBit/s / full speed USB does not seem valid for me. I've thought USB Audio 
2 uses high speed mode?
* when trying to play a 24/96 track in Audacious I'm getting "ALSA error: 
snd_pcm_hw_params_set_rate failed: Invalid argument."
* using aplay on the same 24/96 file and plughw instead of hw leads to:
cat /proc/asound/card2/pcm0p/sub0/hw_params 
access: MMAP_INTERLEAVED
format: S32_LE
subformat: STD
channels: 2
rate: 48000 (48000/1)
period_size: 6000
buffer_size: 24001

Additional questions:
* how can I check device capabilities?
* which Alsa version is needed for USB Audio 2?

-- 
Thorsten Mühlfelder
Salix OS: www.salixos.org 
 

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