Hi Stu,
I would be interested in a sub out board, with a crossover control, and db + and - gains. Maybe even another amp remote wire too so you have the option to turn off the sub amp completely.

One of the main reasons i would want this, is to be able to fade the front and rear highs independently of the subs. Right now i have front RCAs going to the front highs, and the rear RCAs to the rear highs, and the sub amp.

But if I’m the only one, then don’t worry about it