This is interesting. I have a Wolfson DAC and noticed this same behavior. I was surprised and didn't think the recording was the same as what I'm hearing. Kind of forgot about it until I saw this post.
I'll have to pay closer attention to this. Lately I haven't been in front of the system but off to the side where Left and Right channel separation is not very noticeable.
I'll have to sit and listen to some music instead of web radio / background. When I hear it again, I'll listen to the same tune in audacity and see if the music swaps channels.