mazian, if you are doing a comparison for your own sake blinding is not necessary but you have to do a "rapid" comparison and you have to be honest with yourself. I have done this many times with recordings that I have both the vinyl and digital copies. You have to be able to switch sources by remote from your listening position. You Q up the digital and analog sources in a synchronized fashion matching levels as closely as possible then switch back and forth between sources. You can only analyze one characteristic at a time, bass, voice, cymbals, image and so forth. The number of switches you can make is infinite. What I find varies depending on what I usually think is mastering technique. Sometimes I prefer the vinyl, sometimes the digital. It always amazes me how dragging a rock through a trench can be even remotely close to raw science.