This Subwoofer looks great and has nice tight bass output. It is reasonably priced to buy. I looked at Polk & others in the same price range before buying this Onkyo SKW204 Primarily as l figured it would fit nicely in my Home theater setup since I wanted a Bass reflex model that has sound output that faces you rather than firing down or has speaker holes on the sides. In the end it turned out to be a good decision as it blended in my setup perfectly. 

By the way, This Subwoofer has the lowest standby hum and provides ample output in the low frequency to provide all the booms and thumps one needs. Yeah but, Just like many reviewers on Amazon has pointed out that the auto 'stand-by' function does not work very well for most TV programs that has very low bass content until you fine tune your Amplifier's LFE or Subwoofer output or completely disable the auto standby feature by a hack!

Here is the location of the Test point P631 use a Jumper to disable Auto Stand-by function:

MAIN PC board assembly "NAAF-8829" inside SKW204

By Default, The auto 'stand-by' function puts the subwoofer into sleep (Stand-by mode) and when it comes out of the standby mode it produces a short click follow by low frequency thump sound which can be very annoying. Granted the feature of fine tuning Amplifier's LFE or Subwoofer output may not be there in all amplifiers or not easy to find out in your Home theater Amplifier system but once you increase the Amplifier's Subwoofer out by +10dB or more and reduce the overall volume output using the knob at the back of subwoofer, this way, the subwoofer stays on (For most period) and the auto 'stand-by' function does not bother me much. I know one can permanently disable this auto 'stand-by' function by shorting the test point P631 (See picture above) on the mainboard inside the subwoofer, but I did not want to void my warranty, so as of yet I have not opened and implemented the hack suggested by some reviewers on Amazon. BTW, If it bothers me too much after the post warranty period I will take action and implement the hack by shorting the test point P631 on the MAIN PC board assembly "NAAF-8829" inside the subwoofer.

So far, I am happy with the unit despite the minor annoyance of the auto 'stand-by' function. Rating with four stars!

If you would like to purchase one from Amazon you can use this link below:

Onkyo SKW204 Bass Reflex Powered Subwoofer (Black)