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. 
uditnaik
I would look at getting a nice dedicated DAC to connect to your pre-amp and then connect the IMAC to the DAC (USB is fine).  The better the DAC, the better sound your going to get.  Honestly, I don't think upgrading the software on your Mac is going help that much.  What's your budget to improve the sound from the computer?  
Just to share my story. I started off using a Mac mini to an Ayre Codex DAC, but I wasn’t happy with the SQ, too much USB jitter. I was thinking about adding all kinds of tweaks like linear power to the Mac and other tweaks (USB isolators, Sonore MicroRendu) and then I realized that with all these tweaks, it would have ended up costing the same as buying a audiophile music server (without all the work), so I ended up buying an Aurender N100H and now the music the Aurender + Ayre Codex can produce is very very good. No jitter. One option is to ditch your iMac and put your music on an Aurender or Melco N1A like audiophile level music server and connect it to a good sounding DAC. It’s a lot of work and money to get computers to sound good but I think your best bang for buck is an upgraded DAC.