Since the source text is rather poetic, or lyrical, I thought the translation could be, too. (Interestingly, our source text here is not an original, but itself a translation from the French.)
I thought of 'assembly', 'gathering', 'gathering-place', or 'ensemble'.

Finally went with 'concert' in the sense of harmony, collaboration, gathering, unity. It also has the musical connotation, of course. And it just seemed a lovely word in a way that 'sum' isn't, quite. Though I like Eileen's translation!

I believe this is the idea behind the words.
Good luck!

I like your own version and some suggestions, just got carried away....

Since it is a marketing slogan, it should be quick and catchy, maybe even make the reader pause and reflect.

Also:
The soul is the set of all passions.
Our passions are our soul. (if the client will let you switch it up).

I also like the ideas about symphony and confluence I suggested to others above, since those words conjure up sophistication, in my mind, anyway.

Best of luck!

x