Attenuator treble bleed?

[Sigesmundninja]

So I have a dr Z Maz 18 that is waking my childran and pissing of my wife every evening. I was thinking it'a time to build me a L-pad attenuator to quiet things down.

I'm probably going to make on following this guide: http://www.theguitarmagazine.com/diy/diy-workshop-build-your-own-attenuator/

In the schematics they have wired a on/off/on switch with two capasitors to act as a bright/off/brighter switch. I was first thinking I would replace this with a 2-pole rotary switch and wire up 5-6 capasitors but then I was thinking it might be better to wire a capacitor blend pot. What do you guys think? Is it ok/safe to this setup, how would I wire it and what would be good cap valurs?

Thank you /Markus