Arduino Zero [SAMD21G18] ADC Sample rate

Hi all! I read on the SAMD21G18 datasheet that the sample rate frequency is up to 350 KS/s.. Does anyone successfully configured the microcontroler to reach this sample rate?
I'm trying to read the 972 pages datasheet but currently I need a quick solution.. I have set the CTRLB register of the ADC so as to reach a 50 KS/s rate, but I still not understand how to change the GCLK_ADC to be feed ba the 48MHz system clock.
Thankyou very much in advance!

Up!

Anyone who solved this problem? Tnx

You may be on your own on this one of course - I know how voluminous the datasheet is for the SAM
chip in the Due, but haven't used the Zero.

I suspect for absolute max rate you have to enable DMA mode and things like that, which alas gets complicated.