I had the same problem and it was due to the factory cable.  Have you just switched sides on cable or used a different cable?

Let me give my impressions of the 4 tubes I have tried in the Vali 2.  For context I am new to the nicer headphone space and currently have HiFiman HE-400i's, newest revision.  Before the Vali 2 I was listening to these with a Fiio E-10k.  While the headphones sounded great with the E10K, it was...

I have to agree, I received ​a 6922EH and JJ EE88CC this week and the Electro Harmonix is head and shoulders above the JJ and stock 6BQ7 for the music I listen to.  Until the 6922EH I was worried I had pretty much thrown away $169 because the Vali 2 with stock tube while smoother than my Fiio...

I'm not sure if it meets your specifications but I had the same issue with a bad stock cord and ordered a 2.5 meter cord off EBay, they do have several lengths to choose from.  It cost under $40 delivered and I received it in 10 days from China to California.  I've been very happy with it.  ...

Hello all I'm new to the forum and jut got the Vali 2 yesterday.  Its my first experience with a tube amp and I'm enjoying the different sound from the Fiio E-10k that I am used to with my 400i's.  That said I think the tube choice is pretty bad, I'd rather have a really mediocre new production...