Well when I got my DAC first, I didn't have the avianos with me. So hooked them up with the now sold polks. The first impressions was WTH. The mids are fine, the highs are good but whats with the bass. The bass seemed to be overly accentuated and the polks were not being able to handle the lows well. Was little disappointed. Still used it for the burnin thing.
Things improved but still the bass was little overpowering so I had to turn down the bass knob a bit to actually get the sound I wanted.
Then came the Avianos. They indeed are GOD sent. They had such a control over the whole spectrum. The highs were good with the polks but after listening to the avianos, I realized how good they sound now.
To me the DAC showed a major improvement in highs and lows. The mids shed all the sibilance they had and the timbre improved but the highs feel so tamed, so softer and nicely put than before. The bass is very fine now. I am not much into techno and other stuff so can't comment about the attack and all but for the kind of music I hear, the accentuated bass, nicely handled by Avianos, threw a new dimension to the mix.
Overall I am very satisfied with the product. In fact highly impressed by the concept of DAC, how they can turn your music into something you never imagined.
There is another aspect to it, though. My wife still doesn't feel any difference. For her, if norah jones is singing, she was singing before and she is singing now

She simply doesn't understand the improvement in the texture, the subtle improvements, liveliness and vivacity, the presence of human touch.
I can very well tell that people who are new to DAC might not even feel that its worth spending so much on these little devices but as you get deeper into the sound, you'll realize how critical these components are.
I am so excited with this DAC thing that I am thinking of stepping up even higher in the chain. Looking at the Benchmark DAC, Peachtree iDAC and MF M1 at the moment. Itching to get them an replace this one. (Damn this cycle never ends !!!!).