What Limitations are there when Restoring Audio?

It is difficult to judge how good a result will be without actually trying some restoration work first, but there are some general rules of thumb. Obviously the main factor is the quality of the original source audio, a perfectly pressed rarely played piece of vinyl will almost certainly be easier to clean up than an ancient, scratched, heavily played album - but then there are occasionally those nice surprises ! Many audio software programmes now offer some restoration tools to some degree or another and are capable of excellent results when used properly. The trouble is that if audio comes to us 'partly' restored it makes it difficult for our equipment to recognise the faults and remove them and therefore limits what we can achieve - so of course you can do your own restoration processing if you are confident it will reach a result that you are happy with, but if you want us to do any restoration work it is usually best to provide us with the original source (or copy of, providing it is well transferred and not topped and tailed as the de-noise process involves taking a sample of noise - usually before the actual track begins)