Yes, that would work. Although the Bluesound Node 2 has the aptX Bluetooth codec, the Apple devices do not yet incorporate aptX at this point like the higher end HTC, LG, Motorola, Samsung, etc. devices do.
I assume you will also have the Bluesound connected to a network, wireless or wired? (I would think so, otherwise you wouldn't need a streamer, just a Bluetooth receiver). If so, you will likely be able to get somewhat better sound quality via Wi-Fi than Bluetooth, as well as have a much greater distance range, while still controlling the device with an app from your phone.
Either way, my preferred first choice would be to connect the Bluesound to your DAC with the coaxial output, using a 75 ohm digital RCA interconnect (vs. the optical output), unless you need the DAC's coaxial input for something else.
Steve