Does my laptop need to be grounded when charging?


I generally leave my MacBook Pro attached to its charger while listening to music files played thru my dac via USB.  I have noticed that when I am barefoot and gently rub my finger over the metal surfaces of the laptop that I feel a slight fuzziness as if there is stray voltage going through me.  It is not a shock per se and the sensation goes away when the charger is unplugged.  The charger does not have a ground prong. Should I ground the metal cover of the laptop? Should I get into the habit of disconnecting the charger when I listen to music files from the laptop?  Is this normal?
jc4659
I don't know if it's normal, but the noise and ground loops of the charger have been well documented. If your DAC does not already include a USB galvanic isolator, it's a good idea to use one. They can be cheap, like $30
Thank you, Erik.  Yes, my dac already employs "galvanic isolation to the outputs" but not really sure if this means I shouldn't be concerned about noise coming into the dac.  Some of these isolators are inexpensive while others such as the Intona or ISO Regen are >$300.  I am currently using a codex.
@jc4659
Is the AC plug on the charger polarized? If not try reversing it 180 in the wall outlet and see if that helps.
som engineers are thinking that the USB issues are lack of a clock signal wire, and noise on the data wires

noise from a charger might affect the latter, but just try it both ways (blinded) on some very clear passages

or get a DAC or other 'boxes' that can reduce these putative problems... do you have a re-clocker?  (I think the regenerator function in the uptone items may be a reclocker)

AND... a used Apple TV3 costs ~~$40 - can then use Airplay for your Redbook data and beam it over WiFi

jc is giving you a very old and very valuable tip