Tony,
First, the MP3's play much louder than the styles and sounds and I think this is because these have been mastered in a Studio as a final mix for distribution and so levels are maximized and it makes finished tracks off of a CD louder/hotter.
Next, I only hear hiss if i turn the vocal volume all the way up. I'm not sure if this is what you are talking about, because most keyboards will produce hiss if there is an open mic input and it's levels are too hot. I do not notice any hiss when playing without the vocal level up high.
I have no problem playing my midi files in the Genesys and I've not had the keyboard lock up on me at all. This is only the first Genesys I've received because only a few came into the country a few weeks ago.
George Kaye
Kaye's Music Scene
Reseda, California
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George Kaye
Kaye's Music Scene (Closed after 51 years)
West Hills, California
(Retired 2021)