Promotional copy - any different in sound quality?

Yes, the promos are much better. I have spent enough time comparing the promo and non-promos of the same. The results are always the same. However, promo copies are often not in good condition.

Most of the WLPs I have are CBS (Columbia/Epic). The ones from the late 50s and early 60s are pressed on quieter vinyl than the standard issues. Same thing with the Mercury promos I have, except the promo labels on these are either gold or sort of peach-colored. I have a few 70s CBS promos too, which have white labels, but don't seem to be of any better quality than the regular issues.

I have a large collection of White Label Promos (WLP)that I have purchased over the years. My view on the sound quality of these promos has changed with the passage of time.

Up until recently I felt the WLP were superior sonically but as my system got better and my record cleaning techniques improved, I use the Walker Prelude record cleaning system, careful listening comparisons with many original pressings of the same record indicate that the WLP do sound on average a little better than the average vinyl pressing but if you acquire 4-6 regular copies of that same record the Promo copy rarely wins in the shoot-out. I no longer look for promos of any kind anymore but instead just look for clean originals and evaluate each copy separately.

Johnny

I still love to play my 6 eye columbia Miles Davis Kind of Blue. Its only better because its the first press of a great classic and still plays wonderfully.