Help with Cana-Kit using TDA2003

[noob for now]

I built 2 of these kits to use with PC speakers.

www.canakit.net/Contents/Items/CK194.asp

Hooked them up with a 12VDC / 1000ma wall wart, http://www.elektrosil.com/Stromverso...c/product9.htm connected inputs to the sound card and all worked well. I bought 2 switched power supplies from PowerStream (12 VDC @ 4.1 A) www.powerstream.com/ac-1245.htmand they wouldn't work. LED on the brick flicks on and off. Doesn't matter where volume pot is set. Obviously it is overloading and shutting off. Undo the power plug and the LED stays on. Next I disconnected the speakers with the same result. Disconnected the inputs from the soundcard and now the LED stays lit when connected to the amp.

Next step is to haul out my old CD player and connect the line outs to the amp inputs and use the Power stream power supply. Now everything works except for a high frequency buzz (switched power supply?) If I touch the metal post for the volume pot, the buzz gets louder in relation to the volume pot position. If I disconnect the inputs the buzz is still there.

2 questions
1) Is the buzz from the switched supply and if so what is the best way to deal with it.
2) Why does the switched supply shut down when connected to sound card but not when connected to CD player?

All components are plugged into the same power bar.

Many thanks in advance to anyone that can help.

[sangram]

You have some sort of ground funnies, I don't exactly know what.

That is what is causing the buzz. I get it too when I connect my Delta 66 to my amp, but not when I have my Antec supply running the PC. Something to do with the internal construction of the supply.

You know I can't see that the body of the volume control is connected to any sort of ground. Sometimes that helps with the buzz.

You may ask a mod to move this to Power supplies section, may be more appropriate there.