Earfun UBoom X - testing a brand new unit (Patreon)

I decided to purchase another UBoom X, meanwhile it would seem they are really gone from amazon.de

After updating to 949, I put it against another unit I had bought some months ago. Here you can hear the difference between both, which is definitely bigger than expected.

Probably due to low quality production the differences can be quite big not only resulting in different frequency response but also more rattling from one unit to the other, which is quite unfortunate. Still I tried to make the Uboom X somehow special, as my original unit had no issues at all and has the deepest bass with least distortion compared to all other units I got afterwards. As this was my reference unit back then, I was sure all units would be more or less like this