Digital tweaks or upgrades that do work

Having lots of computer based audio for over 6 years or more from the 1st Bryston digital player 
which was not always smooth saying with firmware issues, 
currently I have what I feel the best Dac -Streamer high end value in Audio ,the Bricasti M3 with Streamer board Roon ready. Tweaks, upgrades that truly work , taken from their upper end dacs 
Sill points I put the ultra mini  under the dac , and also have a polished slab of granite which makes a outstanding anti vibration piece and a 15x15 piece polished$150:a true bargain , the Still points just add to the musicality ,stereo separation and detail, not cheap $500 retail  but work well.
the Ethernet hub or switch ,the stock netgear is noisy ,a noticeable improvement is the Uptone Audio
Ether Regen which cleans and isolates the signal going to your streamer, 
the Ethernet cables also a very noticeable increase in resolution , I am using the very cost effective 
Wireworld Starlight from modem  to router , and I currently have a long 32 ft run of Beldons top  cat 6 certified 500 MHz , which I will be upgrading with the same Starlight 10 m , the most difference noticed though is from the Uptone Audio  hub to the streamer which I am also using  the Wireworld starlight  cable at $210 a M
a true bargain  cat8; Ethernet cable. Lines are dedicated awg10 -4 wire dual ground , 1 common ground 
1 insulated isolated ground ,  with 2 -5Ft Copper grounding rods. 
and also have a polished slab of granite which makes a outstanding anti vibration piece
I commend you for the tweaks which have brought out the best in your streamer. My 1st efforts in tweaks was with footers. And I studied various materials. I am very leary of granite because it emphasizes the high frequencies which is something my system does not need. If you were having problems with clarity, then granite may be a remedy. But IME IF you want to warm up the presentation wood is a better alternative.
You may already know this. But I thought it worth the mention just in case you don't. That said, if it works for you and you like the sound then that is what its all about
As for a tweak that works, I have my DIY roller blocks/balls under my CDP which adds a lot of improvement to the sound.
Granite rings. Badly. Not good at all. Only reason I use it, didn't know it at the time. It does add mass, and it is stiff, so it can be made to work. Mine is on a sand bed that helps to damp ringing from below, and with Townshend Pods to help isolate the component above.   

That would be a big upgrade, going from Stillpoints to Pods. Another big upgrade would be a QSA fuse. There's a lot more, but you know the first rule of Fight Club? lol!
@audioman58 if you are using a Roon Nucleus then I'd suggest a Teddy Pardo power supply. At $440 it is a well worth upgrade to your streaming enjoyment.
I built a small SS computer last year with Jcat usb,Ethernet cards,  , I am currently looking at  the very good 2 box 
Melco -N10 server  with separate Big Linear power supply.