Are streamers digitally enhanced?

I had a conversation yesterday with a studio engineer friend and I was telling him about the sound of my Innuos Pulse. He has heard my system with the Node 2i and was skeptical about how much difference a better streamer could make. 

After I described improvements in soundstage and overall sound quality he remarked that it sounded like some digital enhancement, similar to a studio plugin, was part of the higher end circuitry. I offered that it was revealing, not enhancing, and he replied "how do you know". 

How do we know? Digital circuitry is controlled by software/algorithms and these can't be readily seen like hardware. When new hardware comes out, reviewers can open the hood and look inside. But what do we know about how streamers or DACs are processing the signal? Is the goal purity or beauty?