RGB and SRGB difference and their use
sRGB is a colorspace. That is, it defines a reference system in which a perceived color can be expressed by three numbers: R, G and B.
If you want to reproduce a color expressed in sRGB value using three LEDs, you have several computations to perform:


First, you have to know the spectrum of the three LED you are using. ( I hope: one green, one red and one blue)
Second you have to build a model that allows you to match the sRGB defined color to a mixture of your three available spectra. If you have the tabulated spectra, you can do this mathematical, but usually, due to dispersion, it's done by measurements.
The use of a colorimeter or a spectrometer is required here.


OR

You don't care to be colorimetrically correct and just match the R, G and B value to the LED power accordingly. You can also set a gain and an offset for every channel, and adjust manually the values until you get an acceptable result. And I you want better result, you can also set a gamma value in addition to your gain and offset.