preamp gain in relation to whole systems help

Ideally the gain of the preamp and power amp, and the output voltage range of the preamp, and the input voltage range of the power amp, should combine such that the volume control is used roughly in the middle of its range (ideally between 10 o'clock and 2 o'clock, although between 9 and 3 may be ok also).

The power output to the speakers will not be affected if that is not satisfied. But if the volume control has to be used at a very low setting, in most cases its resolution (the ability to adjust volume in small increments) will be degraded, and adjustments may not track well between the two channels. If the volume control has to be used at a very high setting, then preamp-generated noise/hiss may become excessive.

Whether the power amp is Class A, AB, or D is not directly related to these issues.

That said, I'm not sure what you mean by "gain of 2," "gain of 8," etc. Is that 2db and 8db (preamps normally have considerably more gain than that), or 2x (two times, which is 6db) and 8x (which is 18db), or some other meaning?

Regards,
-- Al

No, I doubt that is the correct interpretation. Just about any preamp other than a passive one will have considerably more gain than 2 db, and no line-level preamp will have anywhere near 64 db gain (although with a phono stage included that is somewhat in the right ballpark). Also, 62 db gain difference would make more difference than 8 o'clock vs. 11 o'clock on the volume control, I would think.

Changing all those resistors sounds like an awful lot of work, and might cause you to lose the proper logarithmic taper. You WANT the steps down near the bottom of the control range to be larger than the ones near the middle, so that you can reduce the volume to zero and near zero values. And you want the steps near the middle of the range to be small, to allow fine volume adjustments.

A simple solution for the gain of 8 preamp might be to put an in-line 10db pad (fixed attenutor) in series between the preamp and power amp. Look at the specs for preamp maximum output voltage and power amp input voltage or sensitivity to see if that would make sense.

Regards,
-- Al

This attenuator has been recommended by some others here at Audiogon in previous threads:

http://www.rothwellelectronics.co.uk/html/attenuators.html

Regards,
-- Al