Much simpler than you think - join to a tally table on dbo.SOP10200.QUANTITY.
What folks often forget about tally tables is that they are a source of rows as well as numbers.
For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden