Great idea trying out the ole little Creek. I got mine on Ebay for less than $200 and it has surely been worth that for the great remote and excellent sound. That being said, I have heard other passive preamps that sounded better but the Creek is a great little unit. You will get a good idea of the stark difference between the Creek and your NAD, which is an OK sounding piece for what it is but surely not on the same level. Ironically enough, I used an old NAD 3150 as a phono preamp running into one of Stan Warren's early Superphon passive units; did really well at the time, especially when you have NO money to spend!
Not sure of your concern with the Audio Note DAC. What is the ouput? Most are around 2v or so and that should be fine. Cant remember if you said what it was or not. My Rega Planet is 2v and puts out plenty of volume for most material, and this with the lowly ProAcs - not your super sensitive Klipsch!
Let us know...
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ps - See the pic above of the Creek? Notice the all black face without the bright green "Creek" writing? A simple fix here - Just turn the plate around and put the green mess facing the inside. Took 2 minutes and it looks 100 times better.... like a little custom, black, mystery box. Of course, the sound got 200% better....