2.0 DD sounds better on PC stereo speakers than 5.1 DTS HD?

[casspir]

I currently watch BDs on my PC with Genius stereo speakers.

Is it possible that on a PC system with stereo speakers the Dolby Digital 2.0 audio track sounds much better and louder than the 5.1 DTS HD Master Audio track (the volume level is the same, of course)?
For examle, the UK BD release of London Boulevard has two English tracks on the disc: 5.1 DTS HD Master and 2.0 Dolby Digital. When I choose the 2.0 Dolby Digital track in PowerDVD13, I can hear the audio and music much better, it is much louder, etc.

I understand that a 5.1 HD track is not meant for a PC system with 2 speakers and it can sound worse on a stereo system than on a 5.1 surround system, I guess. But is it possible that a 2.0 DD track sounds superior to the 5.1 HD track on a stereo speakers PC?

I want to rip some of my BD movies to the HDD of the PC, but I only want to keep one audio track. If it is really the case that a 2.0 DD sounds better than a 5.1 DTS HD on a PC stereo speaker system, then I have to ditch the 5.1 HD tracks and keep the 2.0 tracks for my PC, I guess. Is that true?

I'm sorry if my question sounds stupid, but I'm really no expert, I have no clue, that's why I am asking. I would appreciate if somebody can enlighten me.

Many thanks!