First Watt to Pass Labs

Not sure impedance is directly (in any way?) related to
sensitivity.

I did read it again, not sure I get your reference though - Larry seems to be referring to issues of gain and input sensitivity. You make a reference to amp impedances and I'm not sure what the relationship is between one and the other - nor do I know that the J2 is in fact any less sensitive than the F3 though it does have much higher input impedance and signifactly more gain (should actually work with a passive and a 2v source, like the B1 for example).

Are the J2 and M2 both designed for similar types of speakers
and the choice would be based on preferred "flavor"
or is one better suited to certain kinds of speakers. Seems
like the J2 power output behaves more like a tube amp (lower
power into 4ohms) and the M2 for like SS (higher power into
4ohm). My speakers are Merlin VSMs which "on paper"
would seem to be well suited to the J2, but I have not heard
either. I have owned the Aleph J and XA30.5 with the Merlins
(smooth, highish impedance, 89db) and they both sounded very
good, but not sure that I did not prefer the J which surprised
me given the price difference at the time (good have been
better compatability with my Joule preamp I owned at the
time). Thoughts?

Jeff1225, your speakers are very sensitive, no?

Nice writeup, thank you Larry.