Seeking advice/tips on improving sound quality

Greetings fellow audiophiles,
Lately I have gravitated towards streaming music from my iMac to a Audioengine B1 bluetooth receiver just for the sake of convenience and the ability to play the same music in my main listening room as well as the patio/backyard (which is extremely convenient when we have large gatherings) The primary system comprises of Mcintosh C27 preamp + Mccormack DNA .5 + Vandersteen 2CE and Vandersteen 2WQ. It's a modest system and works very well. 90% of my audio files on the IMac have been ripped from original cds to Apple lossless format. Although this setup sounds very good, I was curious to know what else can be added to this chain that would bring about significant improvements to the sound quality, i have no experience with any software packages that claim to enhance the sound quality and have occassionally used an Arcam rDAC which has not sounded any better than the dac that's in the Audioengine.