DIY color enhancing shampoo?

I live in South Korea and the hairdressers here are unused to European dark blond hair.
Last summer, for kicks, I began adding a little peroxide occasionally too my shampoo, the result was great, subtle lightening, not to much damage.
Fast forward one year, and I'm no longer happy with how light it is.
I want to do the reverse and go slowly darker, I was able to purchase Revlon Professional Revlonissimo over the counter.
The color is only a very little different from my blond now (9.3).
I was wondering if I can simply add a small amount of the creme-gel color (sans Developer) too my shampoo? Would this work to quietly alter the color of my hair?
Any help or suggestions is appreciated.