First Watt to Pass Labs

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

Read his post again. It's the reason I used insensitive in quotes.

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).

Sensitivity has to do with the magnitude of the input signal (measured in volts/millivolts) needed to achieve full rated output. The F2 requires a fairly hefty signal to reach full output compared with most amps.

This is probably a deliberate design choice. First, it is not so insensitive that the normal output of devices like a CD player would not be adequate. Many owners of extremely high efficiency speakers would welcome being able to crank the volume control past the 7 o'clock position and not have the smallest change in position correspond with huge volume change. The amp is designed for such applications. Also, it may well be the case that not building in "extra" (unneeded) gain in the input/driver stage would have sonic advantages.

I just happen to "need" a bit more gain because my current phono cartridge is quite low in output given the 60 db gain of my phonostage. I don't have noise issues, but, I am nearly out of volume control range when cranking up the volume.

Larryi,

Yes, as someone with high efficiency speakers, I have certainly found that I prefer amps with lower gain for the volume control reasons you mention. With some higher gain amps I found myself using inline -10dB attenuators.

Now with my Atma-sphere S-30, I can use a jumper from Atma-sphere to bypass one pair of the 6SN7s and reduce gain. One less pair of tubes to replace to boot!