I am reading on other boards where they compare the Allo USBBridge and other solutions, including stock Pi4. At least the technical specialists are the opinion not to attach anything unneeded to a pi used as network streamer (even hdmi output....) because this will add some electrical noise (the same stuff you hear when you use a really noisy USB port of a PC) to the USB port and ruins the sound quality. Worst case according to them are USB sticks directly plugged into the Pi, and as I fear the SSD also would be plugged into the Pi via USB it also would add noise.
Now please don't nail me to a cross. I don't know how big the impact is on a Pi. On a PC it was big enough to use the optical output, because on USB the noise was clearly there, even on my small computer speakers.
With this in mind I am still unsure if what the Allo guys are doing with the USBbridge (adding layers and more layers to keep noise away from the USB Port) is just unneeded overhead which adds a nice price tag to the whole setup or if it really makes sense. I am no audiophile fanatic but I don't want to ruin a sound system worth maybe 4k USD by using a Pi (cost: aprox 100 USD total ) instead of a USBBridge (500 USD).
So the best performing gear would be: Allo USBBridge with Shanti LPS. Bridge connected to Ethernet, no other devices attached to it, data stored on a separate NAS drive. If the router is too far away, a wlan repeater is required and not a wifi dongle. And then not the cheapest but "second cheapest" USB cable going into the DAC. Something like a solid made Belkin cable or in my case an Oehlbach USB-Evolution B in the same price range). Stay away from higher priced "audiophile" cables. Only a rip off. What you need is good shielding and solid connectors, that's all.