In this scenario where the remote of the sub has a LPF dial, would it be best to set the dial at the highest frequency setting and use the dsp to set the lpf?
doesnt really matter.... use which ever one has the most options (slope/freq.) and is most easily accessible....or use both and stack em....example: 24db slope on amp + 24db slope on dsp = 48db slope at same frequency.....but if your just gonna use dsp then set amp the highest it will go
you can put it at 200 on the amp and anywhere from 50 to 80 or maybe even 100hz on the dsp depending where your sub blends with your mids. You'll want to play with the slopes. The 200hz on the amp is just a 2ndary buffer just in case the dsp craps itself or something.
I do the same thing with a high pass filter on my tweeter's amplifier channels even though its crossed over on the DSP, i still have a 800hz high pass cross over just in case things go wrong, no bass frequencies gets to the tweeter.