It's small enough to hide round the back😕

Plus it's got input converters for recording analogue and a whole raft of recording/editing software bundled with it.

Admittedly it's intended for home studio use but you cannot deny the quality of the output DAC😁 esp. given the price.

iTunes at 320kbps and lower will seem harsher if you have a full resolution reference and are playing back on good speakers.

You might want to check your settings for iTunes, though. Make sure you have no equalizer, volume leveler, sound enhancers or anything of the like enabled.

After having spent a long time now listening to lossless files, playing back through optical out to either a receiver with a DAC or a stand-alone DAC (or straight to the digital IN on my BL5s), I am no longer able to listen to low resolution files, and particularly not from the analog out on my Macs.
My ears have gotten too attuned to the difference in quality and I pick up on it, particularly with acoustic music. As you say, there's a harshness, a lack of body, that just doesn't set with me.

I don't quite understand how you'll be using the Apogee Duet, though. It's primarily intended as a recording interface between microphones, guitar, keyboard - to the Mac. 

Thanx for your input. I have of course turned off all the settings in iTunes. Do you think the sound would be better through AUX of my BS9000 or is use of the PC2 the same?

 The reason for the duet was really just a lot of raving reviews, comparing it to much more expensive units that just do out. Like this one: http://www.head-fi.org/forums/f7/apogee-duet-dac-rocks-282021/ 

Do you have any other recommendations? 

I think Puncher's recommendation looks very promising:

link

And believe that David Moulton has also made a recommendation as to DAC in the Duet's price category.