Should the power be off every time changing cables?

@almarg  and others...   To clarify, component off or system off?  If the component (for example Pre to Amp), then the Pre or the Amp or Both? Thanks.

Power should always be off otherwise you can blow out a woofer or worse.

Where is Charles Darwin when you need him ?

To clarify, component off or system off? If the component (for example Pre to Amp), then the Pre or the Amp or Both?

@david_ten 

Hi David,

In the case of RCA line-level interconnections, at least, and particularly if the components involved are solid state, I would strongly advise turning both of the interconnected components off before doing anything with the cables. And that applies to connections between source components and preamps, as well as between preamps and power amps.

As I alluded to earlier, when an RCA connector is inserted or removed there is a brief instant during which the signal connection between the two components will be present, while the circuit ground connection between them will not be present. During that instant the signal voltage that will be seen by the component can be just about anything, depending on how circuit grounds and AC safety grounds are interconnected within the two components, and depending on how much AC leakage to chassis occurs within the power transformers of each component. (Such leakage normally occurs to a very small degree, and apart from being a possible contributor to ground loop issues would usually would only become consequential under this kind of circumstance). And many transistors, that might be used in the output stages of line-level components, have very low "absolute maximum ratings" on how much voltage their internal junctions can withstand in a particular direction (e.g. only 5 or 6 volts or so in many cases, if it occurs in the direction of "reverse biasing" their "base-to-emitter junctions").

Also, even if the cables in question are between a source component and a preamp, as I'm sure you are aware best practice is to turn a power amp on last and off first. So if the preamp is to be turned off for purposes of changing its connections to a source component, the power amp should be turned off (first) anyway.  

Best regards, and happy New Year!

-- Al
 

Good Lord! Does anybody ever read the questions any more?

I wonder I still need to turn off the power amp when I change IC cables between preamp and components.

No. Of course not. As anyone above can tell you the instant they come to their senses. You just need to change the source selector on the pre-amp.

I am actually ashamed right now to even be on a site where this is even in question. That's it. Done for the night.