I'm SHOCKED literally .

I put a couple of new components in, and generally shuffled things around in my system last night - and after listening for a couple of hours today - got SERIOUSLY zapped (it was audible) as I touched the Volume knob on the preamp to turn it down. There was some kind of charge build up, and it took a while to drain it all down - I had to (gingerly) touch the knob a couple more times and then hold it until the charge was drained off. My finger still hurts!

This has never happened before - so it's not static from my rug or something. I'll be doing some careful testing tonight, but in the meantime - Any ideas what could cause this???

Possible explanatory variables:

---The "new" items were the preamp (tube) itself, the processor which connects through the Pre's Tape loop, and a Granite Audio power cord with toroidal noise filters at each end connecting the Pre to a surge protector (temporarily). The surge protector has been in use elsewhere with no trouble.

---The new processor is a two prong plug - Polarity?

Tonight I will try running a couple of hours with the processor unplugged and the Tape Monitor OFF to see if I have the same problem. Or if any other equipment has the charge buildup.

Any ideas? Is there a plausible explanation without there being an actual equipment problem?

Do you have a rug in your listening room? Where do you live climate wise, is it dry,or humid important questions to ask yourself. If your room is very dry try a good humidifier. They are very silent and will add moisture to your room. If the problem continues than remove the rug if you have one.I can not answer the question about some equipment holding static charge more than other's, I will leave that to others to answer.
Are you absoluteloy sure it is not a static charge?
It has happened to me as well. It turned out to be static electricity & that some clothing I was wearing did not get a sheet of fabric softner when the clothes were dried, as silly as that sounds.
In the past I got such a shock from my amp. In my case it was because the amp wasn't grounded, a cheater plug/ adaptor was in place. When it's windy and dry I still get mini shocks;and don't use those cheater adaptors. I live in Southern Ca.
Sounds like you have a floating ground on your preamp. You can lift the ground by using a three-to-two prong adapter plug. If there are only two prongs on the preamps plug already, then check to see if you are using balanced cables. It could be that the balanced ground connection is causing the floating voltage from another component, connecting between chassis ground and earth ground.
If it is static charge, I would suggest two simple answers which I do now as I am in the "dry season" and have a woodstove nearby to make things worse. First, touch the wall, wood furniture or metal object to help to neutralize the charge before touching your components and/or second, take your shoes off before touching the stereo system.
It sounds like static to me. This time of year I always touch one of the metal supports of my rack before I touch any gear, to drain the charge.
Thanks for all the suggestions so far - I'm pretty sure it wasn't static, since this has never happened before and my room has been the same for 5 years. The processor has a simple two-prong plug and I reversed it's polarity in the outlet then tried to recreate the situation again and couldn't. So somehow, it may have been that.

I'm going to test the equipment chassis' to see if there is any slight current flow going on. But for now, I'll just have to be careful. Or I'll just ask my wife to change the volume - she's the one who always wants it lowered anyway!
"Or I'll just ask my wife to change the volume - she's the one who always wants it lowered anyway!"

Dude...that's classic!!!
I agree with Stereo Spencer & Jond if it is static electricity. Thats exactly what I was doing, touching a metal object to disharge before touching the stereo until I could figure what was causing the static.

Opalchip keep in mind that static electicity can give you quite a snappy jolt ( is audible as well) as it discharges from your fingers to the volume knob. On occasions I could see the sparks, but very slightly.
same thing just started happening to me. wonder if it causes any damage to the components?
Audiofire5228, yes it can destroy a delicate processor chip used for remote controlled functions. Best to use the remote if you have a static problem until the problem can be resolved. If not remote operated, probably can't hurt too much.
not sure if this makes any sense, but i seperated my previously stacked cd-preamp onto their own shelves and i would say 75 percent of the problem has stopped.........or maybe i just stopped dragging my feet.