Connect the AVR 3805 normally except remove the jumpers linking the speaker terminals of the Polks and connect it only to the bottom or woofer terminals.
Connect the 1612 front speaker outs to the upper tweeter terminals of the Polks.
Connect the AVR3805 front preamp outs to any analog input on the 1612, select that input, select stereo mode, and then adjust the volume of the 1612 while playing music to adjust the levels of the tweeters to the woofers. Then just use the 3805 for all volume adjustments.
After all that it probably will not make all that much of a difference but give it a try.