An external day of Quality is key , for 1 get rid of the wallwart power supplies to the router ,most are modem- router combos ,war wart power supplies Horribke noise makers buy a linear power supply, then a Ethernet bridge LHY-SW8 sell very good LPS also loook on the wall wart most are 12 v and you need 4 amps or more in your LPS.
and SW8 Ethernet switch which gives alot for the money and your Ethernet cables
pin a budget $200 each the Wireworld starlight ,usb cable too same brand these are essential items , the $1k Denafrips Aries 12-1 dac excellent value
and always use respectable power cords it does make a difference , Pangea awg14, Sig MK-2. Use Cardas best #1 Copper and all gold plated Copper connectors