How much of the front end depends on the preamp

I'm using a Rega P5, Rega Exact cart, into a receiver (Yamaha RXV 2095 - MSRP $1600) with phono stage and Vandersteen speakers.

I'm wondering how much of the front end you might consider is the TT? the cart? and the preamp?

Is it as high as 33/33/33?

I learned, in auditioning tables and cartridges that the table was absolutely necessary as a base to build on, and I've started with Rega's "top", but other peoples low-end cartridge.

Would you consider a better cartridge more critical than a preamp? I'm not unhappy with my system, but the inner upgrage worm gnaws at me. Any comments will be carefully read and considered. Thank you.