Is shielding necessary on interconnects & speaker cables

its best to not use shielding...closes in the sound.  If you need it, you need it.

Your best bet with anything like this is to leave that choice to the professionals. In other words do not look for shielded or unshielded. Don't give it a moments consideration. Look only for what sounds good.

Other than phono cables where the signal is in millivolts so must be shielded its unlikely you'll find a shielded interconnect you prefer. But if you do, buy it. Buy the sound not the theory. Every. Single. Time.

When would shielding be necessary? 

@petware when you know you have a lot of induced noise. :)

Like if you are picking up a radio station, or motors or fluorescent lights.

Thanks Erik, 
i was just curious if certain components like dacs  or streamers or turntables warranted shielding or not as a rule or if it's just on a case by case situation.