Naim Nait 5i Bypass issue

Hi everyone,

I'm currently facing an issue with my (beloved) Naim Nait 5i from 2005.
When in Bypass mode I have noises coming up on the speakers.

My setup:

• Naim Nait 5i amp
• Audio-GD 3.32 Dac
• HT Preamp Emotiva UMC-200
• Computer is connected using optical fibre to the Emotiva, and coaxial to the DAC
• Synology NAS connected to DAC with USB

When using the Naim 5i as in integrated with the NAS or PC, no issues.
When in A/V mode through the HT pream (optical f and unity gain) I'm picking all noises from the PC, hard disks, mouse movements..

So far I've tried different things:

• Changed the PC power supply to a gold X-650 Seasonic
• Plug the Naim 5m away from the PC
• Add some ferrite cores on the PC and amplifier power supply lines

What worries me is that those noises are there even with A/V inputs unplugged from the amplifier so it all comes through power lines. Unity gain is amplifying all defects from the power lines..

While looking for a solution I realized that I had quite some "Humming" in A/V mode with no inputs plugged. (Ground loop ..?)

And while checking I also noticed a strong odour around the power supply capacitors in the amp. Could they be dead? No bulging on these BHC 10000uF and 4700uF

MANY thanks for any help or insight.. !!