My speakers are 88-89db at 8 ohms (easy load) in a 140 square foot room: What power amp specs would you recommend assuming a max preamp output of 775mv, in terms of input sensitivity, dB gain, and total watts? Thanks in advance!
Most amplifiers require 1 t0 1.5 v output, to get full output. You are in a small room, with pretty efficent speakers so you really could use any 30 to 40 watt unit. Be aware that as you are running with the volume set to about the two O'clock position just listen, base noise levels will be greater. What unit are you using for a preamp.
It's a Yaqin MS-12B, which I love. I think you're right about the wattage, but if I made my own power amp what input sensitivity/gain do you think would be ideal?
The input gain has nothing to do with what you call 'wattage' which is actually 'power'.
If an amp can deliver 100W output power in 8 ohms, that is 28V RMS.
It then depends on the gain of the amp what input level is needed to get to max output.
Most power amps have a gain between 20 and 30, so that means your input signal for max output would be between 1,4V and just below 1V.
The exact level is not terribly important because you will NEVER send that max level into the amp - that would mean full open level control and that never happens.
Your 0.775V is fine for any practical power amp, because the exact output level is set with your volume control.
You are worrying about a non-problem.
Jan
Most commercial amplifiers for pro sound systems have an input capability of .775V to achieve full power. To be blunt they sound far different than a good Hi Fi amp does.
This thread had been dead for four years. 
Some forums will warn you when you are trying to revive very old (like >1 year old) threads; I think that wouldn't be a bad idea here.
BTW, the MS-12B line stage appears to be a pretty standard ~250V B+ common cathode + cathode follower job of typical (maybe ~15 dB) gain that should need no special treatment in terms of level handling.
Now it's time for this one to
Some forums will warn you when you are trying to revive very old (like >1 year old) threads; I think that wouldn't be a bad idea here.
BTW, the MS-12B line stage appears to be a pretty standard ~250V B+ common cathode + cathode follower job of typical (maybe ~15 dB) gain that should need no special treatment in terms of level handling.
Now it's time for this one to