I disagree that digital reproduction has an "edge", a good DAC/CDP shouldn't sound like that.
I know what you're saying, but I don't think you should assume his setup sounds harsh because he didn't say that in his post.
And the tube buffer isn't necessarily going to smooth out the sound of his setup, IMO that has to do with how good your gear is. My tube preamp was basically a tube buffer, but my setup still had a hardness to it that I wasn't happy with. I just don't think tubes are the solution to everything.