Question about Sennheiser HD 600

It would take too long to explain everything in one comment, https://www.youtube.com/watch

tl;dr no, it depends, if you take the HD600 as a basis, the HD650 have less quality in the vocals and are less "wide".

Both the HD600 and HD650 have advantages and disadvantages, you just have to decide which you like better.

I haven't heard the HD650, but I chose the 600 because it sounds more natural according to several reviews. And that was the decisive point for me. The HD600 really sounds quite neutral and is very suitable for all acoustic recordings.