Hi. Denon 3312. Changed from a 5.1 set-up to 7.1 adding 2 surround back speakers. All worked well as 5.1 and adjustments were made with a sound meter. After hooking the 2 SB speakers the volume level has dropped about 75% in the rear speakers even though they were calibrated with the meter. Can barely hear them. Connections have been double checked, all are correct. Any help would be really appreciated. Thanks. Edward. The only way to hear the surround speakers properly...