Re: FIR filters
I think I need to quote Ivan … “it depends” … probably the best real world example of what you can do with FIR filters with respect to sound quality is the difference between an EAW or Fulcum product when they are “focused” and when they are not.
Generally I would not expect an increase in SPL, but it is possible, a higher crossover slope may take some load off the compression driver and there could also be better summation between bands.
If the speaker components in a line-array are not physically symmetrical, as you move across the coverage pattern the lows and highs can phase cancel because arrival time from each of the divers changes as you move across the pattern (radiation error). If you use brick wall filters this problem can be greatly reduced.
Here are a couple of links that may be of interest
http://dolby.invisionzone.com/index.php?app=core&module=attach§ion=attach&attach_id=8
http://dolby.invisionzone.com/index.php?app=core&module=attach§ion=attach&attach_id=7
...and here is another (complicated) FIR trick ...
http://firmaker.afmg.eu/index.php/downloads.html
