Can a new DAC make a 6 disc changer sound better?

I have an Integra 6 disc changer that I use when I want background music or want to listen to more than one disc at random. I have the digital out running to the DACs in my Integra reciever that I use as my preamp. Are there any external DACs out there that would make this setup sound better or is it a waste of money. I don't understand why the transport would make that much of a difference compared to the DAC. I use a Philips 963 SA when I am doing more serious listening. Would a different CD changer be a better choice than buying a DAC?