I have a high quality passive DIY SEAS 6.5" monitor in my main system with Hypex UCD 180 DIY amp and a WiiM ultra, and turntable. And I am quite happy with that, but it is also 20 years old. I have Edifier M60 on my desktop computer which are amazingly good for the $145 special deal I got on them. They are good at full price. Erin has a good review of them. Spinorama pretty good. Not a main system sound, but good on desktop. I am enjoying and using the Edifiers so much that I am intrigued to get a higher performance all-in-one speaker.
Sure I could go passive and use another amp I have, but that defeats the all-in-one approach and transportable approach.
Yes, a WiiM mini via optical would work for sure into the Coda W, and be cheaper. As to the WiiM app, I am not sure if the app on the Mini basically has the same features as my Ultra, but primarily I just need the PEQ, and I think it does have 10 or 12 bands. I have PEQ dialed in on my main system with the Ultra and it really makes a difference. So yes, if the DAC in KEF can do its thing via optical, and the WiiM app on the mini still EQ, then that is the idea. I have no desire to use any DAC in the streamer and output analog and convert analog to digital via the speakers ADC then back via its DAC. Holy redundancy, Batman.
I was thinking of the KEFs for use either as upgrade on my desktop, as the Edifier has opened up a very new pleasuure in listening in my office. I could also use the Coda W in my living room or with my TV, for which HDMI would be fine, probably even Blutooth. But in listening to the Coda W via a Blue Sound node at the hi-fi store near me, I was very impressed with the sound. Other than in the lowest bass they can rival a lot of passives. They are worthy of being in a main system and offering quality critical listening.
KEF LSX II LT is a good speaker, and on deal at Costco of all places for $599. Not sure you can beat that. Smaller driver though than Coda W, so lower SPL and bass. But in addition to Bluetooth the LSX II LT has full wi-fi with Tidal Connect. So a WiiM not even needed, but KEF app EQ is limited compared to the WiiM app.
I also have in dry dock a DIY Volumio streamer on an Asus Tinker Board (RPi competitor). Works great after a slow boot up, has full PEQ, but no HAT, so at present just USB out. So I could skip a WiiM mini totally and just feed the Coda W with the Tinker Board USB, or any other powered speaker so long as it has USB in. And I could get a HAT if I desired to run an optical or RCA SPIDIF in to another company's speaker that does not have USB in.
The Volumio App has full PEQ,, Tidal Connect and lots of other features, and is actually quite good and very stable for me.