Radio - high pass filter

A simple high pass filter for the radio speakers; I've read this will allow higher volume before distortion by filtering out low frequencies which smaller speakers cant handle.

8ohm speakers, Capacitance to block anything under 150hz thus:
        C = 1/ (2* pi * R * fc)
        C = 1/ (2* 3.14 * 8 * 150)

        C = 0.00013269639066
        C = 132.69639066 uF

Each side has 100uF & 33uF unpolarised capacitors in parallel inserted into the positive line to the speakers:

It didn't seem to make much difference to the sound, and there still appears to be distortion around the 12-13 volume level on the radio. Its entirely possible the calculations I did to select capacitance are off... they were based on some internet research months ago now.

Update - These were removed when the new radio went in, radio is now directly wired to the speakers.