Why is the potentiometer 100k? Let's say I wanted to use the Sweetest Whispers stepped attenuator kit from Bottlehead; it's rated at 15k. What issues would I run into trying to use this in our preamp? Can the Sweet Whispers or the preamp's circuit be modified to make this work properly?

In reality I'll more than likely go with Alps Blue Velvet. Is this a good choice?

.....Colin

The E-T Sweet Whispes is a fine sub. As is the ALps Blue. Pick what ever you and your source are comfortable with. There are as many options for this as there are flavours of coupling cap.
regards,
Douglas

By the way, I've put an OrCad schematic file online. If everyone would rather standardize on a different platform, I'd be happy to upload alternate file types. The nice thing about OrCad is that it has the option of laying out circuit boards and running PSpice analysis. We'll probably not have boards etched, but we may use Spice for some what-if analysis at some point in the future. And having a format for distributon of schematic drawings that allows easy modification of the schematics is nice too.