Devialet Expert isn't good in showing secondary harmonics?

[Jeffaz]

Exactly. He mentioned that the cables would help with these harmonics.

Well, when I want to listen the "warmth" of tubes, I have a small tube buffer (Little Bear brand), so I can pass the sound through it.

I also use Pure Music Player on a Mac Mini. This player supports VST and AU audio plug-ins, and there are tube amp plug-ins for free on Internet.

So, I have tubes, both real and virtual.