Quick lesson on resitive loads from an EE:
When adding resistors in series, the total resistance adds sequentially. If R1 is 6 Ohms (as is the case for the VP150, not 4 as suggested above) and R2 is 6 Ohms, the two in series (+ of one connected to - of the other and the + of the first connected to your receiver's + with the minus of the other connected to the - of the receiver) add to 12 Ohms. I don't know enough about receiver fault tollerances to know whether or not that would be high enough to trigger a protection circuit and turn off the unit, but it would half your power output.
Adding resistors in parallel is basically the inverse. If RT is the total resistance, it looks like this:
1/RT = 1/(R1 + R2 + R3 + ... + RN)
If all the loads are the same value, that works out to dividing the that value by the number of loads. In the case of the VP150, that means a 3 Ohm load which again might trigger some sort of fault circuit, I don't know. It would also effectively double the power draw from your amp, minus whatever voodoo they've employed.
Bottom line, call your amp manufacturer and find out if it has any goofy circuit or if this could be damaging.
