I don't know of a better "bridge" either and would suggest you consider a wired approach....assuming you haven't already done so. It seems as if you have a pretty good DAC and a wired solution could very well improve sound quality quite a bit. According to some, airport express in particular does not sound as good as a wired approach.
I stream music from a macbook to a few different airport expresses in the home and have very rarely ever noticed any dropouts. In fact it is extremely stable, so I wondering if your airport equipment is older. Does your router use 802.11g or n? If it is a or b, that may be the problem.