I, too, figured the FP was not suitable for volume control due to the stepped switch. So for the lowest noise, while still using the SEX you would set the FP as loud as possible and keep the SEX as low as possible?
It's complicated; that's why I wrote a white paper (on the Bottlehead / Community page) about signal to noise ratio. Setting the SEX control so that the Foreplay uses mostly the upper settings lets it work at its best.
Still, the whole issue of level controls is difficult. The original Foreplay - way back, more than 15 years ago - had two carbon potentiometers. We got lots of complaints that it was hard to keep equal gain, and we also found by experimenting that switched attenuators sounded better - so the Sweet Whispers was born, as the cheapest possible switched attenuator. By the time we put together the Foreplay III, incorporating most of the audibly-significant mods that had developed over the years, we re-designed the switch and now call it "Sweetest Whispers". (We also incorporated a slightly more reliable switch.) And we included several series resistors to adjust the overall gain. Still, the 3dB steps are fairly large and the switch is not as reliable as I wish. Unfortunately, truly reliable switches are hard to come by and very expensive. Regular volume controls (stereo dual potentiometers) that sound good are also expensive, and exhibit poor tracking at low settings. Conventional volume+balance controls cost twice as much (twice as many pots), have more complex circuitry, have interaction problems, and restrict the available replacement options. Remote control is yet another whole can of worms.
Given this situation, so far we have stayed with the inexpensive options, allowing individuals to easily replace them with a control of your choice. We are still struggling with what to do in the next preamp.
