Start with L2 Strategy #1 or #2, listen to music for a couple weeks, and see if you hear any benefits. If you do not perceive any benefits, stay with what you have and forget about network tweaks for now.
If you perceive a difference, you may want to move on to L3. Why L3?
Layer 3 adds the ability to route traffic from one subnet to another. No longer are you cut off from one another. This routing module allows devices on VLAN1 to communicate with VLAN2 (and vice versa). This means your Windows PC (VLAN1) can now access your music on the NAS (VLAN2).
This is similar to having a big L2 network where all devices can talk to each other, with a big difference. Device only talk to others if there is a need to. Unnecessary traffic like broadcast, and query packets no longer flood the network. So you still maintain a good degree of network isolation, and throughput is not affected.
The routing module does not really have to super fast. This is because traffic between NAS ⇄ media player is already working at wire speed (same VLAN) when it’s connected to the same switch (the traffic stays within the switch and never made it’s way to the router!). With L3 setup, you can now use your tablet (on VLAN1) to directly remote control your media player (on VLAN2). This still keep unnecessary network traffic to a bare minimum.
You can combine your dual NICs machines and effectively double the bandwidth (Not supported with Ubiquiti Unfi) or reduce latency.
This is going to be even harder to setup.
Routing Jumbo frames can be problematic.