How to make the download ringring tones louder and stronger in OT535

I have download some ringring tones ( midi ) to OT 535 via PC SUITE.

The downloaded ringring tones are VERY VERY SOFT ( VERY VERY WEAK ).

Then I use " psmplayer" to increase the sound intensity up to 127 %
( maximum setting ).
The modified ringring tones shown some improvement, a bit louder than before.

But the download ringring tones are still TOO SOFT/ TOO WEAK when compare with the existing/ original ringring tones in OT 535.

Anybody can tell me how to make the download ringring louder and stronger ?

Is there any softwares can increase the intensity of download ringring tones ? ( e.g. more than 127 % )

Thank you very much !!