I recently purchased an HP Touchsmart as an extra PC for my kitchen area.  While the integrated Beats audio speakers sound decent, I'd like to utilize the available subwoofer out port.  The only problem is that I cannot seem to find any computer sized subwoofers that aren't part of a 2.1 or greater set.  I don't need the satellite speakers and none of those sets have inputs directly into the subwoofers.
 
Can anyone point me in the right direction?  I just need a computer sized subwoofer that I can use the subwoofer port with.  HP made one a couple years ago called the Pulse but it doesn't seem available anymore.
 
Thanks in advance!