This really isn't a McIntosh question, IMHO, but I'll comment on it.
I used to use a SB - the first gen version - years ago with my Mac setup in its various combinations of speakers. It was great back then as there were fewer options online than we have today. The hardest part was getting all the software up and running and getting the box to talk to the software; all early-adopter issues, of course.
As to how it will sound, there are too many variables to really be able to predict: streaming rates, encoded music rates and methods, download speeds, etc. I can tell you that my use for it was to stream music while working at home. It does this great. My test is to see if I find the desire to turn the rig off after a few hours. This isn't the case so it was a keeper for many years.
BTW, did I try the various tweeks like analog power supplies, etc? Yep. Did they make a lot of difference? Not that much. The biggest improvement came when I figured out how to get the grounding done right to lower the noise floor and to get rid of the cheezy in-line power bricks that came with the laptop I use. That's the source of the noise that really affect sonic quality, IME.
Why don't I still have it? Well, I upgraded to a Presonus FireStudio when I started making recordings for the band I play in. It now doubles as the SB equivalent. Is it miles better than an SB? Nope. I just don't get to use the SB software anymore.
BTW, I use FooBar2000 as my main playback engine. I rarely listen to the digitized music I have on the home network. That's reserved for travel, flights and the iPhone/iPad. Rather, I use some of the online streaming services out of Europe for jazz and classical. Its great!
Hope that helps.
Cheers,
David
