What are the AWM technical specifications?
is it based on a 16 bits patterns sampled at 44Khz?
are there different AWM quality levels?
any document/link available?
Thanks.

AWM stands for "Advanced Wave Memory". It is Yamaha's proprietary brand for sample playback synthesis. According to me, there's no public document about it, so, you'll have a hard time finding specs of AWM. But, basically, there's two standards for AWM: the original AWM and AWM2. Both use 16 bits digital sampling except that AWM2 uses some kinds of filters during the sampling process in order to get better samples. As for sampling rate, there's no standard. Therefore, some AWM sources may either have 22 Khz samples or 44 Khz.