Thanks for the recommendations, will have to check them out. I happen to already have a copy of Adler's Orchestration with the CDs, it's a truly brilliant work fully worth the investment imo, considering the amount I've already learnt from it. Twentieth-Century Harmony has intrigued me for a while now, will get a copy shortly, along with the other books, which were unfamilar to me, but definitely look like the sort of thing I am after.
Thanks again :toothygrin: