I need to design a 2nd order

**RC**low pass filter for a PWM that has a frequency of 488.28Hz. The DC component is at the lowest frequency, so my cut-off frequency of the filter should be as small as possible. Until now i designed a 2nd order filter like this: R1=R2=10K and C1=C2=470nF. Calculating the cut-off frequency it results 33Hz (good enough) - i have simulated this circuit but the cut-off is at 14Hz and i also implemented in real life and i still get 14Hz. It has to do with the parasitic resistance/capacitance of the components. But this is not why i am here.

The output of this 2nd order filter is connected at the input of an OP-AMP (so it`s a HIGH impedance input). I have seen on some website that i should increase R2 10 times, and decrease C2 10 times, it has something to do with the impedance and cascading 2 1st order filters. I know how to calculate the input/output impedance of a 1st order filter, but i don`t know how they influence each other. How important are these impedances, and how can i achieve the best results using this filter?!

What should i consider in building it?

PS: when R1=R2 and C1=C2 the Q factor was 0.33 (using an online calculator), but increasing R2 10 times, and decreasing C2 10 times, the Q factor was 0.54...

PS2: i would prefer to keep these values (10K and/or 100K and 470nF and/or 47nF) - i already own these components and i don`t need/want to order new ones.

Thanks in advance!