buzzing from speakers

Inputs (and outputs) are protected to human body model 2kV/2ns standard at best. You can easily get tens of kV on your body in dry room with carpets.

Assembly houses that build boards for many manufacturers have very stringent static control. Everybody is grounded all the time (wrists and shoes) and grounding test is mandatory for every employee in the morning and after the lunch. It is of course possible that they do all of this just to impress me.

Static not only can damage but also change value of components (precision resistors).

Occasionally I also encounter this electrostatic discharge phenomenon when I touch my amps, mainly because of the room that has carpet floor and thick fabric seats. I don't think the amp will be destroyed for this, but one thing is for sure -it ain't doing any good to my body if I get too much of this shock.

Audible hum from speakers may be due to bad tubes, bad power supply, faulty capacitors or any other failing parts within the electronic circuit of the CDP, preamp or amp. You may want to try isolating each item to determine which component is at fault.

Ryder - It depends what you're touching. If it's grounded case then chances of damage are very low. What if you connect and disconnect something and touch input (or output). Even if you discharge yourself by touching ground or grounded case you might have to go to another room (phone call) and charge yourself back walking on the carpet. I found post on Audiogon where somebody damaged speakers by strong static discharge to TT arm. Again - most likely it will not happen but why to risk your investment. Portable humidifier is a very inexpensive (and healthy) way to prevent the problem.

When somebody tells me that you cannot damage SS gear by static I want to ask this person if he is willing to pay others for damage if he is wrong.

As for the hum - how loud is it? When did you notice? (was it sudden?). Have you changed anything (plug to different outlet, add component etc.)

Pickup from the speaker cable is not very likely. In order to get electromagnetic pickup you'll have to have source (transmitting cable) in order of tens of MHz for 2m speaker cable (2m cable is 1/4 wave antenna at 37.5MHz). Capacitive pickup is possible but you would notice change just moving the cable.

Kijanki, I agree it depends on what we're touching. I was referring to the metal casing and switch at the front panel of the amp when I mentioned it is unlikely the component will be damaged with ESD when touching them with bare hands. I wouldn't risk touching the inputs and outputs of the amp at the back panel with my fingers when the amp is running and risk frying myself. In this case, you are correct that the amp or speakers may be damaged. However, this is more towards plugging and unplugging interconnects when the amp is not on standby mode whereby this static electricity will send a loud pop to the speakers that may damage the tweeter or drivers, or the amp. I hope you are referring to this as I believe components won't get damaged if we touch them(the metal casing or knobs at the front panel) that subsequently cause this ESD to take place.

To minimize or eliminate shock when touching the amps, I am now more prudent by touching some wood before I touch the switch on the amp.

Ryder - "Believe" is the right word. Static might zap the input (or output) if you touch it even if you turn equipment off. Damage to speakers was just an example.

Analog Devices application engineer told me once that they had problems with customer's A/D converters loosing linearity after being zapped by static. To me it is even worst than damage (that can be repaired).