I love this EQ but it could be improved. Here are some suggestions;
Dedicated HP & LP filters. Free up the 5 bands for cutting and boosting etc.
There is leakage when using the current F1 (Low Cut) and F5 (High Cut) filters
Variable sloped HP / LP, 48, 24, 12... for steeper cuts
FFT Spectrum Analyser
A simple visual display to see the frequencies, similar to the Sonalksis EQ
All these ideas could be implemented into the current interface, the existing one is great.