Re: watts (vs) volts
You also need to know if the amp uses regulated internal power supplies or not. If it's regulated, there's no difference at all.
Otherwise it depends on the amp design. You can't assume some standard ratio, it doesn't apply to all designs.
1999 Buick Park Ave Ultra
Head Unit: JVC KWHDR720
EQ: Audiocontrol EQL
Front Stage: Hybrid Audio Technologies Imagine 5.25 mids, Morel Maximo tweets
Sub Stage: Boston G3 10", 0.5 cu ft sealed
Amp: PPI Phantom 900.4
Rear Fill: Boston SE953 6X9's