QuickTime midi uneven volume

I want to know if there is any way to configure the midi-player in quicktime player 7.

Because there seems to be a compressor or something that makes the volume a bit low except for the very first transient, or when there is a pause the music, then the next attack is blowing my ears out. I can only find this issue in quicktime, the midi seems fine in sibelius using GM. But I don't want to open sibelius every time i want to listen to a midi-file.

I have searched through some forums, including here, and found nothing similar, am I the only one having this issue?

I am running Yosemite (10.10.3) on a mid 2011 21,5" iMac.

I am also using an external audio-card (Focusrite Scarlett 2i2) but the problem persists without it plugged in.

QuickTime Player 7 - Version 7.6.6 (1710) / QuickTime version 7.7.3 (2890)