Minor Difference between Dacs (Wolfson 8740 vs. PCM 1754)

So I bought this new Onkyo amp with dual Wolfson 8740s and comparing it to my Hegel HD2 dac (PCM 1754). I'm a beginner audiophile and this is my 2nd hifi setup, so I am in a "learning" process. My first setup consisted of Rega Brio 3 with Hegel HD2 and Totem Rainmakers. Sold the rainmakers and brio 3 and going for a setup that has more energy and power.  

I expected a great difference between the two dacs because the Wolfson 8740s should be the superior dac and is used in some of the best dacs on the market. However, there's actually not a whole lot of difference in the sound. I'm using the usb to spdif converter on the Hegel and feeding it into the spdif input on the amp, while having the rca output on the Hegel feeding into the rca input on the amp. The Wolfson 8740 combo does have a higher volume gain than the PCM 1754 combo and has slightly more lower bass. Other than that the sound characteristics between the two dacs are very similar. I tried telling them apart, but it was very difficult. I don't have golden ears but can always tell a difference between different cables.  

I really don't understand why Whathifi gave the Hegel HD2 3/5 stars when it is very close to the performance of the Wolfsons. Other magazines that I have read have given the Hegel HD2 full marks. It does have a lower gain but when you turn up the volume, it sounds quite similar to the Wolfsons and is slightly more smoother.  Quite impressive for a small dac.