I have a setup feeding a G96/G68 through an HD621 into a pair of DSP 6000s. The source separation is much better I obtain on than a second setup where a G92 feeds directly into a pair of DSP 8000s, or on a third setup where a 800/861v4.2 feeds directly into 5 DSP 6000s. I don't know what an apodizing filter really does but I'm delighted with the result.

Sys1:818v3,2x8000SE,Sony654KTV,Roon,UHD722,OppoUDP-203,QNAP48TBserver
Sys2:861v8,2x8000SE,2x5200,Roon,Nakamichi Dragon,Beogram2400.