Headphone volume swells at power up for a minute, is this normal?

[Gonzo]

I just purchased a microbrute. I have aquestion regarding start up.

First of all, after powering on and without touching any sliders or knobs, but playing the keys, the volume through headphones varies from medium to soft and finally resting on the last set volume once it was powered off previously. This process takes anywhere between 20 seconds to 45 seconds to even out the volume right after powering on.

Is this normal? It's almost like it is warming up. Warming up for solid state?

[Gonzo]

I sent this back since Arturia gave no response.

I don't know if this is normal or not. Seems strange for a 'solid state' device having to warm up as if it had tubes inside.