You didn't mention the "ultra-low".... is it on or off?
If the cable is messed up, you could have been using only one amp.......
As for the bass thing, nope, not ridiculous.........
Low end doesn't carry well.
Low end takes relatively way more power to get as loud as mids.
You don't HEAR low end as well as mids
Lows leak out of the room everywhere, thru wood floors, walls, ceilings, doors...
So, cranking the lows ends up using most of your power to try to fill the place with fundamental, which is a losing proposition anyway since they leak out of the room all over.
Having all that EQ on the lows may be trying to get 12 or 15 dB more out in the lows than the mids. That means you are putting maybe
16 times more power into the low lows than into the rest of the sound.....
It should be pretty obvious that will re-balance your sound well into the harder-to-hear "mud range".
The -15 dB isn't helping any either, it just lowers your volume and forces you to dime everything.
If everything is correct, you should have guitarists weeping and small animals dropping dead out in front of you with that setup.
Engage "mono". Use a cable wired 1+2+ at the amp end and 1+ 1- at the speaker end, plugged into the mono output. plug cable into 4 ohm cabinet...... result 1200W (rms) capability.
As far as "liberal ratings", if that means we "add a few watts for luck", I happen to know that ain't quite right.... if we say it, it does it.
I think we just give you too many EQ options.......