Would an external clock “help” in this signal chain?

Some great advice here I very much appreciate, thank you.
 

So the accessory modules that each offered sonic improvements are mere bandaids for a non audiophile streamer (WiiM Ultra) caused set of issues? 

My complaint is a kind of harshness I thought was inherent in anything approaching a resolving system. I turned toward more musical components like a tube pre, Gustard R26 and Linton speakers yet it’s still there.
 

An analogy I can make would be like when I first played with a snare drum as a kid. For months I was fascinated/enthralled but then one day the raspy sizzle bit a little too hard and I almost felt an aversion to it. I was drawn instead to the rounder sound of the tom.
 

So what would be some top streamers? Or should I be looking for a Streamer/DAC? I don’t use a computer to stream but rather the Tidal App on my phone (and gf uses Spotify) so whatever I do needs to work similarly. 
 

The Gustard R26 sounds so much better than the chip based DACs I’ve tried so I probably prefer a ladder design over chip based. Supposedly the R26 can stream via LAN but I’ve yet to figure it out. 
 

The WiFi Extender is a neat idea. Perhaps I need to try that soon as well. 

Can I keep the R26 and just get a better streamer to save some money? 
 

Are none of the ‘gizmos’ useful? I saw them as tools but if they’re redundant that’s another story.
 

Another thing I like about the WiiM that I’m hoping it’s replacement would have is an EQ. 

Here is a great video comparison I found that demonstrates exactly what I’m hearing. So yes I need to find a suitable replacement any with an EQ?

https://youtu.be/DCNPls8DJus?si=nWRFCdxTI5iYb6pL

Have you tried other tubes in your preamp?  I get a big variation in sound by changing tubes.  They don't all sound the same. 

What XLR interconnects (the Cinnamon is digital) and speaker cables are you using?  The SU6 is probably cleaning up lot of the issues of the Wiim, so to address the harshness you’re perceiving I’d be looking at the DAC and amp as the most likely places to change your sound for the better.  Personally I’d start with the amp as your DAC is neutral but not inherently harsh or hard sounding, and a warmer/more refined sounding amp might be your best bet for getting the sound you want.  Either way, what’s your budget and are you looking new or used?