first you need convert mp3 to wave file.
Not sure how long (time) is supported by Pa4x, but let say is fit limitation.
On Pa3x is max size 2MB and 100000 samples, means depends on HZ / Rate you get max time length.
Using some PC audio software you can check exactly how many samples is.
So, sometimes if is to many samples you can low quality, Hz or Rate.
Korg Pa3x support 8 or 16bit and 8 to 44100Hz Rate.
44100Hz give you 44100 samples per second, with limit 1,048,576 samples at this rate you can get max 1,048,576:44100=23.77 seconds long sample, but if you lower to 22050Hz you can get twice longer.
I hope you understand concept.

check this post, I did explain there how can be done for Pad.
http://www.korgforums.com/forum/phpBB2/ ... 17&start=2
If your speech is to long you need to split for 2 or more and do more pads.
Edit: correct calculation

Nemik
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