I have a raspberry pi 3 and hifiberry DAC+ Pro
The PSU is a linear PSU from Audiophonics "AUDIOPHONICS Linear Regulated Power Supply 5V 2A 15VA With USB".
The music is stored on the sd card, no ethernet cable plugged, no usb drive.
I use the latest version of volumio, up to date.
When i connect the earphones trought RCA the sound is great, no noise and a very nice and good quality.
The HIFIberry does a very good job and i would like to listen to the music trough the amplifier then...
When i connect Hifiberry to the Harmann Kardon HK 430 on "Aux" trough RCA there is a background noise, it rumble and sizzle, loud enough to be not acceptable to listen.
Independant from the volume and important enough to mask the sound in quiet moment of music.
I try to connect the PSU from the Raspberry on a different electrical power socket to prevent groud loop and it's the same issue.
It is the same behavior with the official Rasperry powersupply.
I also have a turntable on this amplifier and i have any issue with the sound quality of the turntable on the phono input.
I have try the line-in with a dvd-player with the same RCA cable and the sound is excellent.
On the same line-in the DVD-player sound great, the Raspberry sound great with the headphone but when i connect the Raspberry on the line-in it's sizzling.
I don't understand how can i fix that, if someone has an idea it will be very appreciated
Thanks for reading