I built a Lightspeed attenuator pre-amp over 10 years ago (could be longer!) and I have used it every day since. It is a passive pre, but it sounds anything but passive to me. There are not really any moving parts as the pot is used as a voltage regulator to the Light Dependant Resistors (LDRs) The parts count is very low and my DIY jobbie cost under £30 to build. I did add a remote controlled pot and you could also add switching if you need more than one input.
Diyaudio has a very long thread about it in which you may see my Moniker.