I recently changed one Shunyata SR-Z1 and a standard Leviton 20A for two Shunyata CopperCONN and the improvements they brought was staggering. I am often satisfied with some upgrades I do, sometimes a bit let down by others, but with the CopperCONN everything was just right on everything. I don't recall an upgrade I made that was as perfect as this one. For my system, especially for the DAC (BDA-3 like you have) that was plugged in the Leviton, it was like a DAC upgrade. Not sure if you have seen my humble review about the CopperCONN but you can have a look here:
https://www.audioaficionado.org/showthread.php?t=48241
I agree that 300$ for an outlet is expensive if you look at it from a DIY perspective, but from a audiophile point of view, it's almost a bargain for the improvements they immediately bring to system, especially when compared to top of the line power cords or USB cables.