I had a chance to play with my little DSO Nano digital 'scope and I thought I'd share what it told me about my system.
First I wanted to find the maximum volume setting from my HU. I monitored the front speaker outputs and input a 100Hz 0 dB source in the CD player. Classic clipping at 34/50 volume. With a -5dB source I could get to 38/50. I decided that 32/50 was my max setting. Note the voltage is 24v p-p which is battery rails. This is with engine off:
Next I checked the output of my David Navone LOC at 40 Hz and volume 32/50:
Well now, that's a funky waveform. It cleaned up to a nice sine wave at 100 Hz but I think I'll send this to David Navone and ask him wtf.
My final revalation was when setting the gain on my sub amp (bridged rear channels) at 40 Hz volume 32/50:
The revalation is that with engine not running I only get 22.9 vrms = 131 watts before clipping. I started the engine and at 13.5 vdc I could get 200 watts. I did not expect that much difference. And no wonder my G3 sub barely moves...
What a useful tool this is. Worth the 80 bucks.