What an absolute star!!! Thank you so much. After creating this thread, I saw another which mentioned using lists and it was on my "Upgrade list" after I got the basics of this sorted out. You were absolutely right about confusing UpperBounds and Array Lengths. I'm afraid I simply copied and pasted your code and it works brilliantly. But rest assured, I will analyse the code because that first part (chunks length at index 4) really confuses me.
Also you must be a mindreader, because that last little bit about playing directly from memory was also on my "Upgrade list". This is my first foray into this kind of thing and I found it a bit overwhelming.
I would have given you some more rep but I need to spread it around a bit first