My system:
AVR: Yamaha RX-V385 70W per two channels 20Hz to 20kHz 8Ω 0.09% THD, dynamic power 110W 8Ω/130W 6Ω/160W 4Ω/180W 2Ω
left center right speakers: Klipsch SF-1 40Hz to 20kHz ±3dB, 94dB SPL at 1W at 1m
surround speakers: Klipsch SB-1 60Hz to 20kHz ±3dB, 92dB SPL at 1W at 1m
subwoofer: Hsu Research VTF-3 HO (bass extension: 16Hz/1 port open)
disc player: Sony UBP-800M2 4K Bluray, DVD, CD, SACD, DVD-Audio
TV: Vizio P659-G1
I allow YPAO Yamaha Parametric Acoustic Optimizer to run, then disable the Parametric Equalizer PEQ, keep the bass management crossover frequency but set the front left center right speakers from "large" to "small" to actually use bass management, keep the front left center right speakers and subwoofer distance but set the surround speakers to minimum distance, and set all speaker levels to 0dB and adjust the subwoofer volume at the subwoofer volume control by ear. Sometimes I set all speakers to "large" so the subwoofer is LFE only. I set the surround speakers to minimum distance maximum delay because there are listening positions that are farther from the front speakers and closer to the surround speakers than the position of the YPAO microphone at front center seat.
I used to have a Klipsch SC.5 center speaker, but I didn't like the sound. I don't like the sound of most small horizontal center speakers. They don't integrate well with larger left and right speakers. I prefer the sound of a phantom center to a small horizontal center speaker. I set the center speaker to "none" and used only left and right front speakers before I had room for an additional tower speaker.
My front left and right speakers are only about 45° apart rather than 60° or 90° apart, slightly wider than the width of my video display. I am satisfied with the stereo soundstage width. I don't like the sound of front left and right speakers too far apart.
I like the sound of surround speakers, but I frequently set surround speakers to "none" and remove the surround speakers and wire because they are annoying obstacles for people moving around the room.
I don't like the sound of Yamaha Virtual CINEMA FRONT feature.
I detest the sound of Yamaha DSP programs, so I use unprocessed straight decode.
Microphones don't hear like ears. I don't trust any automated system to set frequency equalization.
I consider typical music average level to be peak level -20dB.
THX standard level is 85dB SPL at -20dB full scale at the listening position.
NIOSH Recommended Exposure Limits are 85dB SPL for 8 hours and 105dB SPL for 4 minutes 43 seconds.
94dB SPL at 1W at 1m equals 112dB SPL at 70W at 1m equals 102dB SPL at 70W at 10.6ft, not considering room gain.
I use 14AWG stranded copper speaker wire.
I am certain I could have better sound if I had better equipment and a better room, but I am satisfied with the system I have.