Hello ​@michaelweku, welcome back!

Would placing the era 300 upside down around 50cm from ceiling affect sound quality that much?

Perceptually how would it differ from placing them at ear level?

It depends on the exact location the Sonos Era 300’s are placed, the room size and overall room structure.

Most of the issues due to the factors I mentioned above, can be resolved completely or greatly improved by doing a Trueplay tuning after every different setup placement.

In the end, it’s really up to what sounds best to you, so you can just try and see.

Maybe other users in our Community can share their experience in regards to placing the surrounds at ear level or mounted on the ceiling.

I hope this helps.