UPDATE 2 for those, who is still interested. Today I received a brand new Eclipse with V4.10. For comparison a have an old Eclipse running V4.01. I did the test two as described above.

Results:

Old unit V4.01 – no self oscillation on startup with preset 901, thus no squealing noise.

New unit V4.10 – squealing feedback noise at the output. Reloading this preset does not help. But the sqealing does not occur if you restart with activated bypass.

Assuming the hardware is identical, it should be something in the new software. For me, it’s not a big deal, but I hope I could help others with this information. And of course, I would appreciate it, if Eventide will consider this bug in the next software update.

P.S.: I still didn’t scheck the bug from the test one (see above).