Not sure I understand OP's question, but for surround HDMI goes to my Bryston SP3 processor that sends balanced LR to a by-pass input of my Ayre KX-5 Twenty preamp and balanced surround directly to a pair of NAD stereo amps that drive side and rear KEF LS50s. I think surround adds a sense of depth to certain concert and opera Blu-rays.
Bryston admirers have argued that the SP3 can do both stereo and surround, so there's no need for a separate preamp. IIRC the MSRP of the SP3 was about $10K.