Sequential Pro 3 – recurring loud white noise when powered, second repair already. anyone else?

I’m currently sending my Sequential Pro 3 back for repair for the second time in a row through Thomann.

For the second time on a brand-new unit, I’m getting very loud white noise (~30 dB) whenever the Pro 3 is connected to the wall with the power brick. The noise goes straight into my UAD audio interface and makes the synth basically unusable.

Honestly, it’s been a complete waste of time so far. I bought it in October, and in four months I’ve barely been able to play it more than a few days in total.

After the first repair, I asked Thomann what Sequential had actually fixed. Their answer was:

I received the Pro 3 back… and one week later the exact same problem returned.

So effectively: repaired → one week OK → same defect again.

I should also mention:

• None of my other ~10 synths have any noise or grounding issues.
• I tested the Pro 3 on a single isolated power source to rule out electrical interference.
• Same result every time — loud white noise as soon as it’s powered.

Has anyone else experienced:

• recurring motherboard issues on the Pro 3?
• loud white noise when powered?
• repeated failures even after Sequential repairs?

At this point I’m trying to understand whether this is a known QC issue or if I’ve just been extremely unlucky. I’m becoming increasingly concerned - I invested €2,000 in this instrument, and after two identical failures and repairs, the issue persists. If the defect occurs again, I could end up stuck in a cycle of repairs without ever having a reliable, usable product.