The most useful addition would be a global high pass filter. Why? Many solo performers use portable amplification systems like the Bose s1 that just can’t reproduce lows very well. The small woofer just overloads with most files that work no problem on our regular full duty PA systems. This feature must be global so it can be turned on and off depending on the pa being used. It needs to be fully adjustable to accommodate the pa in use.
Thanks