I am very much thankful to
@elangoas and
@Amarendra who build my courage to integrate two AVR in Pre-Power combination. This experiment was only possible due to kind guidance and information from both FM.
Most of time we upgrade from old AVR to new AVR in the search of more channels , more power or more features and old AVR become idle or redundant . As most of new avr come with nine channels of amplification and eleven channels of processing for complete 7.2.4 mode, additional two channel power amplifier become necessity . Even for an nine channels AVR , it is difficult to power all nine channels for optimum performance level and run out of power. In this case, we can use our old avr to power additional two channels either for 7.2.4 mode or to share the load from nine channels avr for better performance. Most of older avr doesn't have pre in but still we can use it's analog line input to power additional channels. Following is the procedure...
Today afternoon I have successfully connected two avr in Pre-Power mode. Here Marantz NR1608 is working as pre amplifler and Denon AVR 2113 work as power amp . Marantz front pre out is connected to CD analog line in of Denon . Both avr operated in Pure Direct mode. Initially I have set the volume limit of -25 db on both the receiver. Source was Tidal on laptop desktop app through HDMI port to Marantz. I have started volume control from -60 db on Marantz and -50db on Denon . Then gradually decrease volume by -10 db on each unit until Denon on -10db and Marantz on -20 db. Finally set Denon on 0db and Marantz on -18db to achieve regular listing level. ( Finally I set volume limit to 0db on Denon and -15db on Marantz for safe usage so that now , I can't go below volume limit from volume dial unless until I am not changing the limits ). Listen few tracks and noticed improvement in sound ....System become more subtle and detail, better micro dynamics with bold vocals , low end little tight and agile but not deeper.
System experimented in stereo mode only . Will do in HT mode later on......