Powering a Passive subwoofer.

Finally completed my prototype DIY sub. Has 2-8" woofs in parallel in a 2.3 cuft sealed box and front firing. I am using an old style plate amp at 70 watts. Sounds ok, but it can be better.

Choices are:
Adire or Kiego? plate amps.
Get an Adcom,Hk or whatever amp with a X-30 box or a auto crossover. Probably get a good price on a used set up.
I would not mind, but what I would really like to try is a Bryston Powerpack 120 and a Marchland crossover. Little too expensive right now.

Any ideas, suggestions or experience would help.
My Audio Aero Prima integrated amp has a pre-out. My main speakers will be used from the AA, not the plate amp or whatever.
Your DIY sounds like a fun project. Which drivers did you use?

I own an NHT SW3p passive sub and have been considering some DIY projects with the NHT 1259 driver it uses for a possible stereo sub set up. I have the NHT SA-3 amp with built-in crossover. It works quite well, but I've had much better success using the Paradigm X-30 with a Bryston 4B. Although the SA-3 is made for the SW3p, the Bryston exudes superior control, pitch and extension. I'm only using one channel of the 4B which is easier on the amp, but may eventually use both.

The Marchand would be nice, but I can understand your hesitancy because of the price.
The discontinued Electron Kinetics Eagle 2 has superb grip and power in the bottom end. Unfortunately there are none for sale right now, but they do come up from time to time, generally in the $400 ballpark.

In the meantime, you might try wiring the drivers in your sub in series. While the wattage output of your amp will go down, the damping factor (control it exerts over woofer motion) will go up, and you may find it's a net improvement.
I tried a NHT amp and found the 120watt amp could not control my 10" sub as well as my 45watt Harmon Kardon amp. I would stay away from class G amps, and go with A/B amps.
Yes, class G amps are capable of putting up big wattage numbers, but they're like cars that put out a lot of ponies but have no low end torque.
Thanks for the responses, I sure appreciate it. The woofers are Zetagcorp 8" used in there G4 speakers. They have a cast frame, copper magnesium cone and rear vented. I bought these for close to nothing just to experiment with. I have a pair of Kinima G1 which sound fantastic; I just want a little more bottom end. My plan was to make a stereo pair, but the room is to compact for it. The only way to make a stereo pair was to make them 27" high and put my G1s on them. That meant getting rid of my Osiris stands. Not yet.

Well the idea of a class G amp is history, so it looks like getting a AB power amp and a X-30 or auto crossover.

Again, thanks for the responses.
If you can find a Janis 1/a sub amp and crossover you would be happy. This is quite a clean amp. Only 100 watts @ 8ohms or 200 @4ohms but it extremely tight and by using its built in crossover (they don't get any better), you can blend it with the speakers perfectly. You can find one of these for around $250 if you search.

Janis was created for high end audio, not theater. It performs best from 20 to 100hz. I was amazed with the build quality and heavy guage internal wiring. Currently, I'm using it with Nelson Reed subs and don't even notice that I have a sub in the system-isn't that how it's supposed to work?