One of the best ways to get sounds is to record them yurself.
Use an audio in/out cable and a sound recorder/mixer program to do this. (MS sound recorder willl work to record the sound in .wav format as AH requires.
Mono (single channel) sounds are 100% compatable, but some stereo sounds will work also. Engine's can be done in stereo, where as guns cannot.
I have some raw sounds I have harvested from sims such as
CFS CFS2 B17 IL2 and a few otheres. Post your email and i will send youi a sample, if you like it, I will tell you how to record and mix your own sounds to be compatible with AH.
Mitsus sound pack is an awsome collection, but there is a certain freedom in being able to match the sounds you think go with a particular aircraft to suit YOUR taste while, perhaps, disrequarding historicla accuracy.