Just did a routine calibration of my speaker levels, and found that I had to knock my LFE pre-out on my AVR down from -3.0 db to -5.0 db. My PB Plus/2 has been up and running a couple months now. I initially set it up to run about 5.0 db hot over the rest of my speakers, and I guess over the last couple months its broken in quite a bit. Just an FYI for those of you who haven't calibrated in a while. I expected it to brake in, just not that significantly.
I have one of those Kill-A-Watt deals to measure power consumption and measured my SVS sub at 18 watts a normal levels and ~26 watts at full tilt reference levels...double-checked it even. I thought something was wrong with the meter, but my receiver was pulling 76-125 watts, my PC 150 watts at idle, Sony laptop - 47 watts so I think the meter is ok. Could the SVS be this efficient?
Keep in mind, that meter is reading consumption, and not amplifier output. Also keep in mind that is a class D amp, which doesn't generate a lot of heat. They run 90% efficient, where a class A/B amp as in your receiver is roughly 50% efficient.
A large, ported box should be extremely efficient, espeically with a BASH amp.
Try your meter on a hair dryer on high, an iron heated up, and toaster oven heated up. Also try it on a simple lamp with a 100 watt bulb.
I played Tupac Shakur "Hail Mary" lots of ~20Hz bass. I totally forgot about the benefits of a BASH amp so I guess these result really aren't a surprise.
Those are all good suggestions to test, but I borrowed the Kill-A-Watt from a buddy and already gave it back so no more testing. The box did say 0.2% accuracy. I tried it on my brother's color laser printer while printing: 850 watts max. My 50" LG plasma takes 49 watts turned off (!) and 450 watts while on.
Upon further reading, it seems the low wattage used by your subwoofer (and receiver) at reference levels is probably accurate and is due to the exponential nature of sound. With sound, the power has an exponential relationship to the perceived volume, such that the difference between 2 watts and 20 watts is perceived as the same as 20 watts vs. 200 watts.
Maybe your system only has capacity for a 20% increase in perceived volume before you max it, but that last 20% would require a multiple of the power that you were using at reference levels.
I probably could have turned it up louder, but it was already rattling the walls. The 20x14 room gave out before the sub (corner loaded) so maybe I wasn't maxing it out as I thought, explaining the low consumption. I just bought a kill-a-watt of my own from ebay so now I can test at my own pace.
What you are reading is the RMS wattage use. Since an audio signal, especially to a sub, is more not there than it is there, your average power useage is very low. If you want to see how much it can draw, run a 20Hz sine wave at full volume. Then you should see power consumption close to the full capability of the amp