weird noise from analog distortion unit

[echoplex]

Hi folks,

I've got a Niio Analog Track Thickener. It's an analog distortion unit + passive EQ.
All of a sudden now, I turned it on yesterdays and realized there's some crazy noise coming out of the unit with nothing even plugged in. It's not super loud but still clearly audible. I've attached a screenshot of the EQ to show levels and spectrum.

I wonder where's that coming from and why?!
Last month I replaced one of its toggle switches. But when I tested it right after, everything was okay.
Now I put it back on after a while and there is this noise.
BTW the unit has a switching-mode power supply, if that's of any importance.

Any clue where I can start troubleshooting?
Thanks in advance

P.S: I recorded the noise. Maybe that give you a hint (it's 25dB boosted to make it better audible for you)
https://soundcloud.com/user-179496819/niio-noise

 

[cyrano]

Sounds like PSU noise. Recap the PSU?

 

[echoplex]

Sounds like PSU noise. Recap the PSU?

Hmm not sure. The unit is not exactly old or vintage that it would need recap.
But yeah I might need to check the caps still.

 

[cyrano]

I've never heard of Niio, so I don't know, but the PSU is usually the place to start.