Isolation transformer for laptop charger?


Would using an isolation transformer on a MacBook Pro power supply (charger) help to block noise going back into the same circuit which feeds my other audio equipment?  The USB output side of the same laptop goes into an ISO Regen with its own linear power supply which then feeds my DAC.  I assume the MacBook charger is a SMPS which are known to be very noisy.  I'm not an EE so hoping that this isn't a ridiculous question.
jc4659
I assume the MacBook charger is a SMPS which are known to be very noisy.
Unplug the charger, use the internal battery of the MacBook Pro play some music and see if you can hear a different.
Maybe a LPS?
https://www.computeraudiophile.com/forums/topic/17840-linear-power-supply-for-a-macbookpro/
@imhififan,Thanks for the link and the suggestion.  The MBP should run quietest from its battery I would think.  if it makes a difference then all I need to do is remember to disconnect the charger when listening to digital files, and more importantly, remember to reconnect it when I'm done!  I own several isolation transformers but use only one to isolate my preamp.  I found that it works best in this location.  Adding additional ISO trannies to other components was detrimental to the sound.  Nevertheless I am fascinated by these devices. 
detrimental?  when used on the amp?

maybe they aren't sized correctly?
randy-11
1,800 posts                                                                         12-18-2017 1:44am

detrimental? when used on the amp?

maybe they aren’t sized correctly
That and are the secondary outputs of the transformers AC polarity in phase with one another. Also if the 120V AC wall mains power is directly used to feed any other associated equipment, that is connected together by ICs, is/are the transformer/s output AC polarity in phase with the wall outlet AC polarity.
If this means that the "hot" slot is consistently the shorter one (across all outlets used for my audio system) then I can get a "polarity tester" and check it.
jc4659 OP
120 posts                                                                      12-18-2017 11:16am

If this means that the "hot" slot is consistently the shorter one (across all outlets used for my audio system) then I can get a "polarity tester" and check it.
That should be a given. IF the output of the transformer/s is wired correctly as a Grounded Power System.

What I am talking about if you use a volt meter and insert one test lead probe in the Hot contact slot of the outlet fed from the output of one transformer, and insert the other test lead probe in the Hot contact slot of the outlet on the output of another transformer you should measure zero volt nominal volts. That means the two secondary windings are in phase with each other. If you measure 240V then they are out of phase with each other. Same test can be preformed from the output of the transformer to the Hot contact of the mains wall receptacle outlet. Zero volt nominal in phase, 240V nominal out of phase.

Jim
Got it.  Thanks, Jim! 
Imhififan:. I took your advice and unplugged the charger and holy cow what a difference.  The noise floor must have dropped.  The music became more dynamic, clear, holographic, and the soundstage opened up.  And best of all this tweak was free.  Thank you!
@jc4659
Glad my suggestion helped.
if it makes a difference then all I need to do is remember to disconnect the charger when listening to digital files, and more importantly, remember to reconnect it when I’m done!
Maybe you can add a current sensing relay/switch to your system to automatically connect/disconnect the charger.
http://www.ebay.com/bhp/current-sensing-relay

Happy holidays
I don't think so but thanks for the suggestion 🙂