Alto Professional APX1000, Class D, Digital Power Amp 2x250W @ 8ohm 2x400W @ 4ohm. 12.1lbs 1000 Watts at 8  bridged mono 2 x 500 Watts at 4 ; 2 x 250 Watts at 8 Efficient Class D power Balanced combo input jacks Lightweight, two rack-space design