Having tried every portable device, PC, and Mac I can say with certainty, depending on your other components, the returns are exceptional to at or above your average component cost. [I do not mean blindly using cost as a proxy for sound quality and compatibility at any given cost level… you must due the work to find the very best component]. So, for instance $5K streamer is probably going to be well worth it if your DAC is $5K and you preamp is worth around $5K…etc. This is a generality to point out how very important they are. I could easily see a $12K streamer very appropriate for some systems with an average $5K component level. Anyway, they are really important.
My most expensive (other than speakers) is my streamer (it does not have a DAC). It cost $22K and I feel was one of the best investments/ value for the money in my system. I have not tried and more expensive streamers, I can confirm no diminishing returns up to here. My streamer produces sound quality at the same level as my analog end and CD player.