Thanks again. I'm marking this as answered.
One final question about S/N ratio related to the above discussion:
With a digital system (e.g. a sound card with line-in --> A/D converter), say the peak input voltage for full scale of the A/D is 3.0V. Say the RMS total noise in some measurement BW is 5 uVrms. Is the S/N ratio (ignoring any weighting) specified as the ratio of this full scale value to rms noise: 20Log10(3.0/5e-6) =~ 116 dB or is the specification relative to the full scale RMS value for a sine-wave (which would give a S/N 3 dB lower) ?
(btw nice Jazzmaster ... black pickups?)