I have used my RPi
3 streamer via USB to my Emotiva XDA-1 DAC, running Volumio. Absolutely no problems, it was pretty much plug and play!
I have since moved over to an Allo Piano 2.1 on that device. And, I just set up a PiZero streamer for the garage using the Allo Piano HAT (not the 2.1 variety on that setup).
For troubleshooting, can you get any audio through the 3.5mm jack? How about audio over HDMI? Also, try a different audio source! It should be easy to plug in a USB drive with a few files, or go into the configs and set up a web radio channel, also easy. EDIT: Are you sure your power supply is robust enough to do what you are trying to do?
I suspect you have a simple configuration problem. I can try to poke around in my Volumio settings and see if I can help, but it may be a few days before I can get to it.
It should also be noted that you can perform all sorts of configs through the command line on the RPi! It seems like you won't have the experience on this, but google is your friend. In particular, I had to do this on one of my arcade machine builds where I used an HDMI to VGA converter. I had to use the command line to force the RPi to output the VGA signal over HDMI rather than the normal HDMI signal. Fun stuff!
You should realize, there really is no value in the extra horsepower and cost of the Pi4 vs. 3 in this application. Now, if the USB is really better for streaming, then there is value of the 4 vs. 3, but I am skeptical! The catch is that I will never choose USB as my primary connection (for anything, not just audio), if I can help it, just from my various USB experiences and woes over the years (granted, most of my problems with USB have been in industrial applications at work, and USB is not a good option in an industrial setting). Now, I do want to move up to a Pi 4 for my video game emulation! In that application, the extra horsepower has a distinct advantage.
EDIT: To me, the biggest advantage of the RPi streamers is the ability to transmit the digi stream to the DAC using the I2S protocol. Should be obvious, but using the USB cxn bypasses that advantage.
ALSO--HOW LONG IS YOUR USB CABLE??? DON'T GO OVER 6 FT!
Adding some reference material:
en.wikipedia.org
USB cables are limited in length, as the standard was intended for peripherals on the same table-top, not between rooms or buildings. However, a USB port can be connected to a gateway that accesses distant devices.
