I tried the 75% vol thing and didnt like it. I turned the gains down so I can max out the vol with no distortion. I heard about the HU distorting signal at max vol but my system sounds great and clear this way.
i turn my 780mp up to 19/62 max. really slamming loud at that volume it almost hurts. I have BBE on +4 which makes a big difference SLA is on +4 and "Loud" is turned on too. thats how my unit sounds best to me.