Yes, I asked for a separate noise filter almost as soon as I had got my A4, there are 8 blanked out encoders on the noise page.....
Thanks for all the replies, I have started work on this and it is probably going to take a little while, since the A4 is not really designed for drums I'm having to find a few workarounds for certain types of sound, some of which I have not thought of yet.
Stay tuned