Audio Systems: 2 amps 1 sub., 4 ohms, db increase

Question
I am trying to figure out if it would be possible to hook up two amps to my one sub. Here are the specs:

MTX 9500 Thunder Series 15" Sub (many watts)

Amps:

Kenwood 800 and a Kenwood 1800 KAC mono. If you need more information on the amps please let me know. Thanks for your help in advance!  

Answer
As far as I know this sub comes only in a single voice coil of 4 ohms impedance.  Therefore, you can drive it only with one amplifier terminal.

You cannot parallel amplifiers onto one speaker because the internal impedance of the other amp is very low and will spoil each other.

You can, however, bridge two amps so they drive as though they were one amplifier.

To do bridging they SHOULD be identical amplifiers AND it would be nice if one or the other had a bridge input so the phase can be inverted for bridging.  However, I don't think these two amps are similar enough to bridge and get good performance and neither of them have an inverting switch for driving in bridge mode.

Therefore, I must advise you to forgo paralleling them.

NOTE:  Either of these amps will drive the MTX thunder sub nicely.  I am wondering why you want to put two amps on it?  If you need more power you will need much more than the sum of those two to make a substantial audio improvement.  Why?  Because doubling the power gives a 3 db increase in audio level.  It takes about 2.5db for the human ear to hear a difference in level.  To get a big increase or kick up in power out you would need to triple, quadruple or even 10 times power kick up.

Hope this helps.  Let me know if you need more or if you have any question about my comments.
C