Pros would still score quite well using your mid-level clubs and an el cheapo ball.
Back in the day playing real golf, my handicap went down when I upgraded my clubs/ball.
My biggest improvement on drives with a driver came from upgrading from steel to a composite shaft, a driver face with less loft, and a swing weight of D2.
My biggest improvement relative to irons came from 4 changes:
1. Going from investment cast to forged club heads (Ben Hogan Apex Percussion Center irons w/a thin top line and a pulled heel.)
2. Going from regular to stiff shafts (Hogan #4 shafts).
3. Changing from regular grips w/reminder ribbed grips to velvet cord grips with no reminder rib.
4. Having the loft and lie of the forged blades regularly adjusted for my swing.