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
If the goal is to improve the sound from your main system at the source to your preamp I suggest a playback program such as mentioned here and purchasing a used DAC.

I use Pure Music program and PM allows a 15 day trial period. There are many others. I would purchase the DAC prior to giving any program a try. 
I guess based on everyone's feedback the lowest common denominator is a DAC. For some odd reason my Arcam RDac doesn't jive with the Macintosh pre amp and when I turn up the volume all the way to the max I get a sound level that is moderately acceptable. Hence I am a little reluctant to purchase a DAC only to find that I am still experiencing the same issues. I will take my C27 to local dealers to find a day that can actually work well with it.

Do you have the system on a dedicated line, and if not, have you ever considered doing a dedicated line with upgraded outlet?

The weak link is your source.  There are various options as mentioned CDP, DAC, build your own server which will sound better than the MAC, etc.  Best option is a really good DAC IMO this will give you the biggest improvement.  You really don't describe what you are searching for so it is hard to know what to advise you on.  It is best to mention what music you listen to and where is lacks what you would like to change.

Happy Listening. 
Bigkidz, you hit it on the nail. Unfortunately I don't know what I am looking for myself outside of just exploring what can help improve the current sound. I predominantly listen to classic rock and roll (mostly Floyd, Led Zep, Who) and then jazz (Dave Brubeck, Miles, Monk etc) and then a few odd categories in between at times. My desire to improve the sound came up when I noticed differences between CDs that I was playing to the corresponding recording streamed from the iMac. The difference was primarily in the separation of instruments which sounded very good irrespective of the source on the jazz recordings but not so much on the rock and roll ones. Hence I started questioning whether the recordings themselves were the culprit or it was something in the setup that needed a boost...Looks like all roads are currently leading to a good DAC so I will explore that option. I guess my final goal is to have the ability to get CD like sound but through the convenience of a music organizer like iTunes etc. so that I can listen to various different songs/artists without loading/unloading cds.