Yea it's possible. I was able to convert a song into a SFIV stage music , which uses .AAX using Goshane's CSB Packer . Tools here: http://www.megaupload.com/?d=STCGAXC1
It needs to be Wav → ADX → AAX in order . You may need to adjust the pitch and have all wave forms in mono . But again just guessing as it has been a while since I last did a conversion .
Thanks, but it seems to not work for Sonic Generations AAX files. They keep getting corrupted when I covert the adx to aax. I'm using ADXencd, it has support for looping.
Did your converted .AAX files play on VGMStream ? If I recall you weren't supposed to add looping information when you make the .ADX , but instead it was supposed to be split in two .ADX forms , in which one stream ends , the other .ADX plays. But again not sure if this was the full process since it did took me a lot of trial and error .
PS : If using this setup , this would go against the mono channels rule.