I believe most audiophiles agree that having a router separated from the modem is an improvement in sound quality and provides better wi-fi coverage. I experienced both upgrades in my system when I added a TP-Link C9 Archer router.
Some have found that removing wi-fi from the router improves the sound. I can turn off wi-fi in my router, but I detect no change in sound quality when I do so.
A Zero-Zone 3.3A linear power supply on the router did improve sound quality, and sounded better than an iFi iPower Elite that I borrowed for a couple of weeks. An inexpensive Tirstrup AC power cable from Amazon was another audible improvement.
A Network Acoustics Muon was a step backwards when I tried it between my EtherRegen and exaSound PlayPoint streamer, but was a sonic upgrade when used between my router and Silent Angel Bonn N8 switch. I would have kept it, but the 100Mbps bottleneck was unacceptable in that location.
I tried separating the router from my switch using fiber optics (TP-Link MC220L with iPower X and Finisar FTLX1475D3BTL, smf, MikroTik CSR-305 with Teddy Pardo 12/2 and Finisar FTLF1318P3BTL). This was good, but needlessly complex. I replaced the fiber break with an iFi LAN iSilencer and I am happy with the result. Hard to compare, but I think the LAN Isolator is better. I redeployed the fiber setup to my desktop system, separate from the main audio chain. (My main audio system uses a more sophisticated fiber break).
As to the main question "Routers more Impactful than Switches?", you need both, but IMO a switch has a greater impact on sound quality, if only because it is closer to the DAC.
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