Al and Ralph, both the ARC Ref 3 and 5 literature recommends that the minimum combined load on the Main outputs is 20K Ohms. My amp is the ARC VS-115 which has an input impedance of 300K Ohms (balanced) -- so no problem there. If you pull my threads, you'll see where I got into a problem was when I asymetrically loaded the 2nd Main output with a 20K Ohm load. Main 1 -- VS 115 (balanced) 300K Ohms; Main 2 --self powered subwoofer (SE) 20K Ohms.
As I mentioned in my old threads, the solution was that Tom Tutay designed and built an impedance buffer device that summed the left and right channels without shorting the Ref 3/5 output Mains and enabled me to load Main 2 (self powered woofer) with a balanced input having 330K Ohms impedance. So my overall preamp output impedance load is 157K Ohms -- well above the recommended minimum.
Result -- tighter and more extended bass. Possibly more open midrange. Per ARC, symetrically loading the Ref 3/5 will also extend tube life -- but what do I know???? FWIW.
As I mentioned in my old threads, the solution was that Tom Tutay designed and built an impedance buffer device that summed the left and right channels without shorting the Ref 3/5 output Mains and enabled me to load Main 2 (self powered woofer) with a balanced input having 330K Ohms impedance. So my overall preamp output impedance load is 157K Ohms -- well above the recommended minimum.
Result -- tighter and more extended bass. Possibly more open midrange. Per ARC, symetrically loading the Ref 3/5 will also extend tube life -- but what do I know???? FWIW.