I guess the real question is which cinema you went to for that first viewing? Did you go to a big screen, which might have been showing a 70mm print with 6-track stereo, or a smaller theatre showing regular 35mm (with Dolby Stereo if you were lucky)?
I went to a small theater in a small town. I seem to remember it was a “normal” sized screen, so based on what you said it was probably “regular 35mm” showing. Funny you ask about Dolby, I remember seeing speakers on the side walls and even at the age of 8 I could tell the sound was out of balance and should have been better! From there came my lifelong desire to hear SW the way George intended it.