Comment 4 for bug 1286021

https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1316305

do you mean surround21 not yet available in Ubuntu 14.04 LTS ?

Profili:
  input:analog-stereo: Stereo analogico input (sinks: 0, sources: 1, priority. 60)
  output:analog-stereo: Stereo analogico output (sinks: 1, sources: 0, priority. 6000)
  output:analog-stereo+input:analog-stereo: Duplex stereo analogico (sinks: 1, sources: 1, priority. 6060)
  output:analog-surround-40: Surround analogico 4.0 output (sinks: 1, sources: 0, priority. 700)
  output:analog-surround-40+input:analog-stereo: Surround analogico 4.0 output + Stereo analogico input (sinks: 1, sources: 1, priority. 760)
  output:analog-surround-21: Surround analogico 2.1 output (sinks: 1, sources: 0, priority. 800)
  output:analog-surround-21+input:analog-stereo: Surround analogico 2.1 output + Stereo analogico input (sinks: 1, sources: 1, priority. 860)
  off: Spento (sinks: 0, sources: 0, priority. 0)
 Profilo attivo: output:analog-surround-21+input:analog-stereo

http://www.maxx.com/asus/

refer to those user guides, look like bass is done by software instead of hardware as user can specify cutoff frequency