Bridge Mode for KG-4s? in 2-Channel Home Audio Posted April 4, 2018 Wow. I just learned that my Pre-Amp, an HK Citation 17s, has two sets of Power Amplifier outputs. The manual even says that two Power Amplifiers may be used at the same time as long as the input impedance of the Amplifiers exceeds 2200 Ohms. I guess I way-over complicated this. I did learn allot though, so thanks again!