If you are using AD authorization, then you would need to use NTFS authorization mode with that--not DMS. DMS mode is useful for non-Windows authorization, such as Custom Directories. It is considered a best practice to group your users into AD groups, and then give the group read access on the QVW.
But if I understood your question correctly, you want to use a combination of AD and custom users. In that case, you do need DMS mode. Configure your LDAP connection and then set up a custom directory with users & groups. You can then specify your users in the document's authorization tab in DOMAIN\User format for AD and User or Group format for custom users.