is this right?

i hooked up my subs and amp differently today, now that i have a bit of knowledge on impedence.  i have a 4 ohm stable amp and 2 - 4 ohm SVC 10" subs.  i hooked them up to get 8 ohm's ( + and - of opposite subs put together and the + on one sub and the - of the other sub go to the amp)  then to get the 4 ohm's required, i hooked up the subs to the MONO speaker connections.  This is they way i understood the way to wire subs someone please let me know if i did it wrong.  Aside from that i installed an active crossover set at 80Hz and 18db (it also has a phase option 0 or 180...not sure what that is?) i also installed an RCA cable from the crossover to the amp which  was modified by 'cutting off the ends of the RCA cables, combining the signal grounds (the outer shield), and then using a 1 kOhm (1/4 watt, 5% tolerance) resistor to each of the center conductors.  I Soldered and insulated the resistors so that I didn't short them prematurely, and then connected the two resistors together. Then i connected the summed signal ground to the shield of the new RCA plug, and the summed center conductor to the center pin of the RCA plug.'  The info for modifying the RCA cable was off the following site. 

  http://www.mobileaudio.com/rac-faq

does the setup sound like its done properly?  or is there something i should change.  I'm really excited about the way it sounds now ...I cant wait to finish the rest of the system.  I have to thank the members on the forum that are helping out and have posted great knowledge on the forum..its AWESOME

I was just reading up the specs again for the amp and i got a little confused and am now wondering the better way of wiring the subs now.

RMS power measured at 12.5V DC:

125W x 1 into a 4 ohm load with less than 1% Thd+N

250W x1 into a 2 ohm load with less than 1% Thd+N

Dynamic Power measured at 14.4V DC:

200W x 1 into a 4 ohm load

350W x 1 into a 2 ohm load

does this mean that the amp is able to operate efficiently at both 2 and 4 ohms?  am I only putting out 125W then?

this is my setup now

Is this What i should be doing then to get the 2 ohm load and 250W?

MTX  - THUNDER 4250D

From what I have found you have a mono sub amp that is designed and engineered to operate at 2 ohms. This is the correct wiring method for you.

The RCA cables were modded awhile ago for a cheap pioneer amp that didnt have the capability of being bridged, so i made this cable so i could get a mono signal to the subs, at least that was and is my understanding of how it works untill i get told otherwise...but it was the perfect length from the crossover to the amp so i used it.  It seems to make a cleaner sound as apposed to straight RCA but i'm not sure if the resistors cut back just the right amount of power (which i should have adjusted with gain) or if the quality of the one RCA cable is that much better (doubt it) or if it just creates a cleaner mono signal having been converted before entering the amp...any thoughts or is it probly just in my head?

I just finished wiring up the subs as per the diagram above (2 ohms) and it sounds pretty amazing, packs quite the punch.  I have 2 of the old skool JBL subs (black with the white raised letters) and i was wondering if i would get a louder and better quality bass if i used a newer, better sub... I'm kinda looking towards Premier subs (i will need 4, with 2 being inverted).  at 110.00 is there a better brand or would ther pretty much stay the same across that price range? this sub is 350W RMS and 800W peak...should i be looking for something with a closer rating to what the amp puts out (would this be underpowering the sub?)

Here are some good answers in this forum search for "underpower".