Gary, Glad to hear you too use lots of Smart sound loops and samples. Yes, they are pre-mastered, just like any loops and samples that are out there, and I have thousands of them too. Yet, in my mixing everything together, I master them even further, mostly in Izotope Ozone 5 professional. As for writing and playing anything myself, yes I do. I have 10 guitars and a keyboard, amps and the whole studio setup. I don't use it very much these days and just have fun doing what I like to do. I play a lot of guitar for me and my wife and make songs up quite a bit, but now that is for our enjoyment in our retirement. I enjoy mixing up the samples I have purchased over the years, as I never did use them much and so now, in my retirement I want to get my moneys worth and so that is what I like to share. Hope this answers your question.
Peace and Blessings, John