When My Arduino SD Card Module Music Player gets connected with USB power line, everything regarding sound output goes smooth and clear
But whenever I connected it to an external power supply source using an adapter via jack pin & 9v socket I am getting a severe humming or noise sound at speakers
What to do ??
Which type of power supply with what parameters i need to have here ?
Please guide !
Thanks 
I once bought a wall wart at a thrift store. It was marked 10 VDC. When it would not work properly, I actually read the label. It was 10 VAC! What does your power supply have on it and where did you get it?
Maybe look into common mode chokes that you could wrap the adapter's AC input cable around?
Does it happen when connected to both the USB and the power supply or only when connected to power supply?
It could be:
To be of more help we need:
How you have your devices connected. i.e. are you connected to a Laptop at the same time.
What board and what power supply do you have.
No only when a power supply is coknexted at 9v socket line
Rest I applied a mobile charger at USB port abd its working fine
Means wirh USB everything is good but not with socket line
Small 12 volts smps type wall wart light weight adapter only and no USB at the sqme time
I use to apply one at a time
Ya I did everything to manage that kind of errors but still having issues with any other enternal unit I am applying
From local shops here abd its smps type marked 12v 2 Amp
I applied other also types but still having issue
Try putting a large capacitor, say 500 MFD, between +12 and Gnd. Make sure the cap is the right way round and rated at at least 25v working.
Ya that i already applied it too with ratings Cap but no change !!
I did so many such things !!
OK. So if it happens when only power supply and no USB is connected, it's not likely a ground noise problem (looks like @JohnRob and I had the same thought there). 12V@2A should be more than USB can provide, so it's likely not an overdriven power supply.
If a large capacitor on the input isn't having an effect, I have to wonder if it's your onboard regulator. Some arduino clones can only take 9V max at Vin (so I've heard, I haven't come across this problem personally), so it's plausible that it's the regulator's reaction to an over-limit input.
Without seeing the actual waveform that the power supply is putting out, that's my best guess.
Just to better understand,
Can you tell us everything that is connected to the Arduino. Also is your bench/table etc made of metal?
How long are the wires from the Arduino to the powersupply.
No its completely wooden table with no power supply board on it
Adapter cables are standard one like
1.5 mtrs
Ya Ya exactly this could be the reason
Its possible as I am working on bread boards too
I am testing it with various units available here
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