any time there is a summing, discrete status is lost. the filters in digital bass management are just that...NOT crossovers.

the HPFs applied to the satellites allow highs to pass, 1 filter applied to each of the 5 (thus, the 5 retain discrete status).

a duplicate signal is sent to a summing block where the LPF is applied (in the case of the triple crossover, three seperate summing blocks).

a final summing block sums the composite redirected bass signal with the LFE signal. thus, the lfe is no longer a discrete channel. the newly created composite signal is called subwoofer.

and then there is the genius who decided to place all of the sub's controls on the BACK panel.