Digital/Optical out from Streaming Devices (Bluesound, Heos, etc) to Preamp- difference?

My experience over the last several years using various devices as source for streaming is I have not heard significant differences among sources. All sources I have used deliver very good results. Changes to sound with various DACs are much more significant.

That’s not to say digital is digital or all devices are the same. They are not. Jitter differences can surely be measured. Things like lengths of wires can even make a difference here. But if all are good quality not cheap to start with, set up well and in good operating order, I’d say there is a chance the differences will be minor or even hard to detect at all.

This has been true for me with various streamers and CD players I have used as digital sources to DACs over the last 8 years or so starting with a Roku Soundbridge unit back then. Switch to newer highly regarded (but not perfect) Squeezebox Touch units a few years later (I still use those as well) made no discernible difference for me.

YMMV. The only way to know the differences between two specific units for certain is to try them and compare.

Also worth noting that there are MAJOR differences I can hear using various software programs on a computer tablet or smartphone. Not all software plays equally well for sure. Resolution of the source material also matters.

thanks for your reply, I have the same experiences as you.  In this situation the only variable is the specific digital output of each device, cabling source (Tidal) and gear is the same/constant.

I am demoing the Heos by Denon, and considering the Bluesound Node 2, but with no difference on the digital output of the 2 units, does't make sense to spend $500 on Bluesound vs. $350 on Heos.

It all depends on how high a resolution system you connect it to. There are audible differences between the digital streamers. IMHO, most of Mapman's comments are spot on; dac differences will be bigger. However, once you settle on a dac, improvements in streaming device will be audible on a good rig. If you never plan on moving beyond an entry level system, it may not matter too much, but in this hobby, the devil is in the details, and they all matter.
I'd suggest trying to demo the devices on a higher end system in addition to your own to get an idea of the how those devices compare. If it doesn't sound like much difference to you, save your money. 
BTW, suggest adding Sonore SonicOrbiter SE and Aurelic Aries Mini to your consideration list. Cheers,
Spencer