Alpine mrp 850m=800rms @2 ohms for $275 shipped,SonicelectronicX.com.Alpine mrp 650m =600rms.Ihave the12w3-3-4(2 of them in vented enclosure)wired to 2 ohms.At first,I had the 650 that put 300 per sub,those are around $200shipped,Sonic/Online -the subs did great.My shop let me try out a 500/1 used,He wanted like 500 for it.I heard the Alpine 650,629rms birthsheeet,had as much power as the 500/1,the 500 has the R.I.P.S. so you always get the 500 rms.I couldn't tellthe difference between the two.I saved about three hundred or so.I now have the mrd-1005 and turn the gains down a little.Those are about 310 dollars shipped.