Thought I would chime in here....
The 500 uses a different/more advanced DSP...I am not sure that the 350 has the same DSP.
The 500 also allows for future remote control via Axioms upcoming electronics (whatever they may be.)
As for settings...I can tell you this thing is loud.... I have had the volume at 9 o'clock and the trim flat. Crossovers are in Bypass, allowing my receiver to handle the sub. I have, at advice, set the level for the sub on my receiver from 0 to -10 and experimented with raising the physical volume on the sub. It makes a BIG difference and is something I would recommend to any and all.
