Then improve it for everything: Movies; Video/Music Programs; or Music only (via Web, Cable, Media) via a separate ’FRONT STEREO SYSTEM’
You need
1. FSS. ’Front Stereo System’ with ’HT Bypass Input’ to receive the AVR’s line level Front Signals.
2. AVR with ’Pre-Out’ for the AVR’s Front Channel line level signals to be sent out to a separate ’Front Stereo System’.
FSS Always drives the Front Speakers. AVR always drives center and all surround channels.
I had it backwards, it became very clear here:
https://forum.audiogon.com/discussions/avr-internal-2-channel-audio-mode-or-ht-bypass-external-equip...
Critically: AVR ON, it controls the Volume including the Front Volume the FSS is amplifying.
Unfortunately, your Sony AVR does not have ’Pre-Out’, fortunately many do, and HT Bypass is gaining understanding.
There is some yap about any chosen AVR’s pre-out signal strength
https://www.avsforum.com/threads/receiver-brands-with-the-best-preouts.3045816/
Anyway, think LONG Now, think best 2 channel sound, then figure out how to use that for your HT Front.
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Bass, Subs: improved bass, make sure it is part of the Front Stereo System IF you want extended bass all the time, even when AVR is off, (large mains, or stereo pair of front firing subs adjacent to smaller mains)
or part of AVR Only, i.e. Single Sub movies only, Dinosaur Stomps ....