Discerning a difference between streamers is difficult...only me or common for all?

I have struggled to appreciate the upgrade to the streamer in my system. A couple years ago I had an Audio Research DAC 8 being fed by a Bluesound Node 2i. I picked up an Aurender N10 and did not appreciate anything so sold the N10. I tried a couple all-in-one units. First was the Aurender A20 and I was happy but curious about dCS. I got a Bartok 2.0 and felt the music was more natural sounding from the Bartok and sold the A20. I have always wanted the Audio Research DAC 9 to match all my other AR gear so got one that showed up on eBay a couple weeks ago. Since I couldn’t use the Bartok to stream I ordered a new Bluesound Node Nano so I could utilize the DAC 9 immediately. The pair sounded wonderful but I did not compare it to the Bartok. I ended up getting a quick buyer and it was already gone. The following week I purchase an Aurender W20. I was prepared to have my mind blown....but no. Some albums I could not tell any difference in the sound and others I think the W20 sounded slightly better but again...nothing huge. For the money and the space the W20 took on my shelf, I sold it. Over the years I always appreciate upgrades for all other components. This makes me feel like I am losing my mind. Have any others experienced this regarding streamers? I want to try more. Auralic and Lumin are on my list.

Thanks,

Dana