Overlap and windowing a signal for signal processing
Don't overlap.  Don't use a Von Hann window.  Zero-pad by at least the length of the impulse response of your desired equalization filter.  Then use an overlap add or overlap save fast convolution method or algorithm to combine your zero-padded and filtered FFT/IFFT blocks.

Otherwise circular convolution artifacts will corrupt (severely distort) your attempts at filtering your signal.

If you want to analyze or visualize the audio, use separate overlapped and windowed FFT blocks, not the ones used for overlap add/save fast convolution filtering.