I have owned a variety of amps, including a Schiit Jotunheim and an SMSL SP200, and this amp blows them out of the water in terms of sound. The soundstage is much more "holographic," the bass does not decrease disproportionately at lower volumes, it has great detail retrieval, and it never comes off as sibilant compared to other amps. Using the S7 with my Beyerdynamic T1.2's and UE 18 Pro's has been a joy.
However, there are two things keeping me from giving this amp 5 stars. First, there is some channel balance at lower volumes. The min of the volume knob is at about 7 o'clock, the sound kicks in at about 7:30, and the left and right channels are unbalanced until about 8 o'clock. The channel imbalance is not as bad as it was on the SP200, but it is there nonetheless.
Next, and much more importantly (to me), is that the volume knob is a little wobbly and as a result, when I turn it the knob will grind against where it's seated leading it to be very scratchy and even stick in place at times. Honestly, it's so bad that I think it is likely a defective unit. If this amp didn't sound so good, this would lead me to give it a horrible review and only 1 or 2 stars. However, because of how much better it sounds than everything else I've tried, I recommend it.