FInally I have a noise issue

@holmz - RE:

Should I wind a copper wire around the thing and attach it to the preamp ground as a test?

Wrap a wire round the neutral of one of the phono plugs and ground it at the outlet

BTW - it could be the souce and NOT the cable

• I had a DVD player that caused hum
  • tried everything but still hummed
• grounding the neutral of an input on the amp fixed it
  • the DVD player had an isolated (i.e. 2 pin) power supply

My Bluesound Node 2 causes a hum...

• i.e. IF, the phono stage (which is correctly grounded) is not connected to the system

Its a common fault with components that have any type of "isolated" power supply, like...

• battery powered components like tablets, phones etc..
• CD/DVD players with 2 pin power supplies
• (Some) Bluiesound products
• many other products like the bluesound

Hope that helps - Steve

Its a common fault with components that have any type of "isolated" power supply, like...

battery powered components like tablets, phones etc..

• CD/DVD players with 2 pin power supplies
• (Some) Bluiesound products
• many other products like the bluesound

Yesterday it was the iPad with the only cord being the earphone.

Last night I noticed I also had the higher frequency noise coming in on the TV input.

This morning I disconnected the USB connecting the RME DAC (ADC) to the computer and the noise went away on all sources.

Next I’ll try and free up a place to plug the laptop into the same strip as the stereo gear.

Sort of defeats the purpose of a 24 bit ADC, when the noise floor is toggling over half of the bits.

Thanks @williewonka 

Seems this new-fangled digital gear isn't foolproof.

A bit like the fact that after 25 or more years of development internet connections still aren't stable.

Hi there,

I sometimes use an iPad as a cable-connected audio source, like I guess many people here do.  I found it is essential to be not charging at the same time.  You must have only the audio headphone/lineout wire connected.  Any other connection will cause two things  a hum loop (line frequency 50 or 60Hz tone) and the horrid switching noise and RF junk that comes out of all basic phone/usb chargers.  It can have a nasty subliminal burbling sound that is not completely audible most of the time but is nevertheless destroying many details in the sound.

With only the one connection from iPad ( or phone) to line-in I find the fidelity is not bad and the noise floor is pretty low.

Hope this helps,