I have no doubt you'd be able to differentiate between CD and vinyl, Harrypt. It would, though be supremely difficult to do a careful level match, that meaning using test tones with a VOM at the speaker terminals. Further, it calls into play just superficial issues such as a stray tick or pop, that all by itself provides the answer. The difference between vinyl, and a CD transcription of vinyl is quite a horse of a different color though. A number of years ago, I transcribed a vinyl recording of 'The Wall' onto a CD and conducted an experiment. Now, the CD version of The Wall is distinctly different from the vinyl apart from ticks, pops and all that good stuff. However, the transcription is incredibly similar. If you make no effort to remove the defects, the resemblance becomes earily more so.
Now, I don't always do DBT's. Sometimes, I simply test people's perceptions without their knowing. I'd broken out my older turntable (from which the recording was made), a no longer made Scottish Transcriptor. It's as manual as you can get. I forget the cartridge on it, but it might've been a Sumiko.
A few friends were coming over to spend some time bs'ing, bbq, beer and a few tunes. Now, they didn't all arrive at the same time. The first person, after coming in, immediately noticed the Transcriptor, encased in glass and was all questions. He asked what I had to play on it. I said want to hear the difference between the CD and vinyl version of The Wall? So we played a few cuts from side one from both versions and he remarked how wonderful the vinyl sounded. It did.
Then everyone else showed up which was really just two other people. Among other things, the talk turned to my 'new' turntable and naturally, people's interests were piqued on the matter of differences in 'The Wall'. So, I played the first side of the CD version and we listened and talked among ourselves. Then I got up, removed the CD and without anyone noticing, slipped in the vinyl copy. I made some changes and cued up the vinyl. What no one knew, is that a bit earlier, I'd disconnected the cables from the turntable to the integrated amp, an older Yamaha. So, the vinyl was spinning but the sound came from copy of the vinyl. The first person said, that's what I was talking about...listen to the difference! All agreed, but then, they had to. The speakers, FWIW, are Whispers not that it matters. The audible differences are clearly evident even on these behemoth Marantz speakers I picked up at a garage sale.
Now, this doesn't prove beyond a shadow of a doubt that vinyl and a CD copy of vinyl are indistinguishable. Frankly, it doesn't rise to a level of statistical signficance. However, done well, to my ears and to many others, they're incredibly similar to the point that people are readily fooled.
If you've read this far, ponder this question. If the master tape or DAT is the holy grail because that's where it all comes from. It's the ultimate source. Which would sound most like the master - a well done vinyl or a well done CD pressing?