HI! A friend of mine has a 2 channel amplifier and a BP box with 2 Woofer in it ( 2x25er). Now we have connected it as follows. Stärker plus to Woofer 1 plus unmd from there further to the Woofer 2 plus. Amplifier minus to Woofer 1 minus and from there further to the Woofer 2 minus. Problem: Bass sounds really tinkering. Let’s just close a Woofer on , it plays wonders bar. Or you have to go from Amplifier to Woofer 1 plus Woofer 1 minus to Woofer 2 plus Woofer 2 minus back to the amplifier! Thanks to Tips!