@maam522a the use of DSP in room adjustments, subwoofer integration, etc.... If I use DSP as a filter to split off my subs is my system no longer analog???
To use signal processing "in room adjustments" for main speakers? Then you've entered the digital domain. Dual output analog preampfification will allow for two discrete analog music and desirably processed low frequency systems.
-3dB subwoofers require standing wave mode positioning for proper room integration. With the exception of a distributed bass array no amount of signal processing and amplifier power can properly correct a subwoofers incorrect room position.
Without an industry standard for subwoofer DSP the level of musical integration with speakers in the analog domain can vary quite dramatically. Despite these inequities many in this hobby believe they have attained perfect speaker integration. Meh, it's all good.