Streamers can offer some improvement and people certainly like them but dropping several thousand for a streamer doesn't appear to get the results for the money. People have done these tests and comparisons at high level evaluations before.
Have a high end tube monoblock system and it is very sensitive to changes even one small tube can produce a far greater result than anticipated.
If you have a mac, any mac, it's Audirvana that makes a big difference. At least I can say from personal experience running it on mac laptops and minis, it's very impressive.
Have been using version 3.5 but Audirvana is out with a relatively new version called Studio. I like version 3.5 so much, I've yet to try Studio. It's that good.