If you have ever tried to integrate a Traditional Powered Subwoofer into a quality 2-channel music system it's likely you have encountered one or more of the following integration issues:
Traditional powered subwoofers are susceptible to low level 60 Hz hum created by ground loops. If your Sub has a faint hum then you likely have a ground loop creating in effect low frequency distortion.
Although vibrating floor & walls might seem like a cool physical effect, vibrating room boundaries create their own sound (distortion) that cloaks the actual music.
Sub hum and vibrating room boundaries compound the issue of muddy sounding or uneven Bass throughout the listening space.
Sub Hum, vibrating Room Boundaries and Muddy Bass all combine to cloak or in a large part mask vocals making them difficult to hear if not indistinguishable.
When using traditional powered subwoofers you are often forced to set the low frequency crossover at 60 Hz or lower to avoid objectionable Bass Artifacts created by a combination of issues noted above.
How many times have you felt compelled to adjust the volume on a traditional powered subwoofer between songs on the same CD? Do you really think this is what the recording engineers intended?