@brunomarcs I sold my Freya plus and shipped it to the guy and he's called and said it's making a crackling noise? Sounds like it's coming from the tubes. Anyone have experience this? Does it in all three modes! The stepped attenuator isn't the problem he says.
If it is happening in all three modes, then I don't think it is the tubes. The Freya + turns off the tubes in the other two modes, so they should have no effect.
Is the sound in both channels or just one? If just one you could have them swap the tubes front to back to see if the problem changes to the other channel. This would show that it is the tubes.
I had a similar problem with the first Freya + that they shipped to me, and it was not the tubes. Not sure what the problem was, but they replaced it immediately.