Kal's words ring true to me. Well, I'd expand on 1. and say that you really don't "need" any of this stuff. I think that goes without saying and none of us would be here if we didn't "want" something more. That said, there are plenty of threads on budget DACs to search out. The good news is that digital tech has advanced at such a rate that you can get a lot more for your $ than say, 10 years ago. The answer to your question is, of course, relative to what you consider decent, and how well your system will respond to your "better" version. I could only guess that an audible improvement on a resolving system is easily in the $500 range and even less, though I don't know the threshold where your investment will not meet with your personal expectations. Plenty available in the 400-600 range that will likely best the DAC in the ROKU (again, an educated guess on my part). Candidates in that range that I'd recommend: PS Audio DLIII and the MHDT Labs Paradisea +. There are others, for sure. But per the sage advice from Kal, consider the rest of your system (just how well it might bring out the differences you are seeking) as well as your own expectations of what "better" is worth in dollars invested.