Some smaller installations where the Terminator connects directly into a WAP may not involve a separate switch, however when building a bigger audio network you will need to employ a network switch.
Switches can be the cause of many problems including latency and gaps in transmission.
The Flexicast Wifi Audio system needs to send up to 10,000 packets per second for each hundred users on the system. This is not ordinarily a problematic figure for the average switch, however with an audio system it must do this extremely reliably and with accurate regularity if not to introduce jitter.
If you are planning many audio channels or a larger number of users, you should allocate some of your budget to a higher quality switch such as an L2 grade which typically utilise more powerful CPUs.
If your WAP includes a built-in switch that has enough ports for your project try to plug your Terminators directly into the switch.
In smaller installations with a short to mid-term expectation of under 30 concurrent users you may be able to delay upgrading your switch until you have enough users to justify it, focussing the budget more on the quality of the WAP.