Ok, won’t say anything about you using Behringer.
In general, you are all over the place. And you seriously seems to think you can get great sounding, gut-wrenching bass for under $700,00. Think again.
The only thing that makes even limited sense is getting the Behringer sub. At 120 LBS it’s not all that heavy for a sub.
Buying a 6000Watt amp for 900Watt speakers is, to be blunt, ridiculous. That has nothing to do with headroom, but everything with killing your speakers (it’s only a matter of time before you forget to turn down your amps when you power things up, hit play and see your cones flying through the air. You mention your speakers have 800W max, but keep your eye on RMS figures. A 1600W/8Ohm amp into 450W/8Ohm speakers = disaster waiting to happen.
Not to mention that it is absolutely and totally impossible to get that kind of QUALITY sound out of a 350bucks amp.
Also you’d need an active crossover with this setup (as with your current setup by the way).
A final note though. You are comparing apples with pears. Your current bass cabs are just that bass cabs. They make up the low end of a two or three way system in normal use, pretty much like the 12″ speakers in your EuroLives. They are NOT, emphasize NOT, SUBwoofers. They will never go low enough to get that pounding bass you are looking for. For that you do need a subwoofer that can go LOWER in frequency than your current bass speakers can.
So, without commenting on the Behringer choice, get the Behringer Sub, it compliments your full ranges, has the necessary crossover. Your entire setup will be active and you can sell off your Peavey Mixer and Bass cabs to some band and use that money towards the extra trolley to roll your sub around.
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