ok, i have a half stack thats a combo 450 watts, its a Behringer. 4x10 speakers, sectioned in two 2x10's running at 8 ohms each, making a 4x10 cabinet that runs at 4 ohms. head which is attached to speaker cabinet, is rated for 4 ohms. cabinet has one 1/4 inch output jack for each 2x10. head has two 1/4 inputs and one speakon input. i want to buy another single 1x15 cabinet, with one 1/4 in. input, one 1/4 in. output, and one speakon input. How do i set this up without making the head go boom. i need this information fairly quick, as i have a gig tomorrow, and i need to buy the cabinet around 4 o'clock. Please and thank you.