Is the Asus Xonar U3 supported?

My experience with the Xonar U3 and 11.10 on a Samsung RV511 laptop has been very good.

Installation is dead simple, just plug in and go to Sound Preferences (right click on Sound icon) and the hardware, input and output tabs selecting in turn the USB Advanced Audio Device. And there you have it, a noticeably improved sound output, haven't used the Xonar with a mic yet so I can't comment on the input capabilities of the Xonar.

The Xonar can also be accessed through alsamixer, not sure whether this is any different to using the Sound Preferences (probably not).

It is supported well as any USB-sound device. Long story: by default I've experienced problem with this sound card (clicking sound). After some investigations I found the problem (wrong sample rate) and here is the solution: By default sample rate has been was set to 44100 which is wrong for this card. To check your configuration run this:

pacmd list-sinks

If it does not display: sample spec: s16le 2ch 48000Hz for your card, you'll need to change it to 48000 in ~/.pulse/daemon.conf by (creating directory and new file if needed) this line should be added (just single line is OK!):

default-sample-rate = 48000

After this sound quality greatly improves and clicking sounds disappear.

Also, both 14.04 and 16.04 sometimes don't switch the output (even worse, sometimes Dummy output appears). Solution:

pulseaudio -k

(once you insert the card). I use pavucontrol to tune volume.