Pass Labs X5 Buzz/Hum

This is my first post, so please be gentle. I’ve got a beautiful Pass Labs X5 that is the backbone of a mixed use Stereo/HT setup. The stereo side drives two channels from an Adcom GFP-750 and the HT side uses the other three channels for my front soundstage being driven by an Onkyo RZ50. I love the aesthetics and sound of the amp, and plan to gift it to my son as an heirloom.

The problem is, it audibly buzzes, and that same buzz comes through the speakers if you get within a foot or so of the speakers, and it’s driving me insane.

I recently had a friend and very competent tech go over the amp, and replaced the main filter caps as a possible solution. We also used some dampening material to try and isolate the toroidal transformer from the case. Neither of those things made a difference.

At this point, I’m wondering if there’s anything that can be done? New transformer potentially?



Hoping a community member, or Mr. Pass himself will be able to assist.

Joined 2002
Paid Member
I'm not sure if I understood you correctly, but are you getting both a mechnical buzz (say from the trasformer) and electrical hum through the speakers?

Have you tried contacting Pass Labs directly? (You can see the customer service email address under "My Pass" here: )
Please include info including serial number in case there are revisions over the product life of the X5)

Since you're in the US, it's certainly feasible for your amp to go back to the factory to be checked out.

Edit: Mighty Zen Mod just posted. Please test for speaker hum with inputs shorted as he suggested.