[LAU] Smallest form factor usb sound device

[hgn]

Hello,

for a new ultra-portable laptop I am looking for a USB sound device to 
do linux low latency audio.
The most important factor is a small size, then audio performance, then 
price.

This is not a full production system but rather a "travel sketchbook", 
but still, that needs low latency and DSP load. What I'm saying is: 
microhpone A->D is not *that* important here, if at all necessary.

I am aware that the Behringer UCA 222 or 202 exists, which has 
dimensions 18,3 x 14 x 3,6 cm according to Amazon.
Is smaller possible?

Yours,
hgn