I've just ordered a 727, and I hope it'll arrive by the end of the week. Concerning the gain mod (i.e. replacing R5 and R6 with 200ohm parts):
Are there any sonic benefits, or is this just for consistency in case one owns multiple Stax amps? If I perform this mod, I'd like to use the same size of MELF resistor for the replacement. Does anyone know what size, power rating etc. would be the right choice?
I believe that spritzer, who first did the feedback mod, later dropped the gain mod and only recommended doing the global negative feedback mod, although I can't seem to find that post. In any case, it is easy to just turn up the volume a bit. You should use 350V rated resistors for the global feedback mod, BTW. You should also check the output voltages after the modification, when the amp has warmed up for 30min or an hour with the cover on, you may need to adjust the balance and offset pots if the output voltages are more than 10-15 volts with respect to ground (balance adjusts the voltage between the positive and negative outputs of the same channel, offset adjusts the voltages of both outputs up or down with respect to ground). Note that the voltage may shift a bit when you remove the cover to do the adjustment so there's no point in being obsessive about it.