I also connected an audio GD NFB-1 2015 with the Sabre ES9018 directly to i2s input from the kali reclocker, and that sounds perfect in my opinion, I also use the allo isolator.
I also use two pairs of good linear power supplies.
I do not experience any harshness in my system.
for this I had a denon da-300usb / rotel ra-12 apmpiler with dac / Cambridge Audio DacMagic 100 and last but not least the normal cambridge dacMagic, and I think the audio gd NFB-1 2015 with the sabre es9018 sound better.
This is a never ending discussion topic and you can read thousands of opinions on this subject. In short; yes USB is to transport bits and it does that quite well with almost every cable. But their are at least 2 problem areas:
Interference which could in some cases even cause bits to be ‘flipped’, meaning what started at a 1 ended on the other end as a 0 because the inteference caused the signal level to change. Other way around could be possible as well. This is not so likely to happen and a proper shielded cable and good wiring practises will prevent this from happening. But it could…
Alternatieve signals, especially current or ground signals from other wires or materials, are carried along with cables between two components and they influence the receiving end. This is the most common issue and DAC chips are extremely sensitive in this area.
So although the bits are just bits and they have been sent along fine, it is the same cable that not only carries these bits but also interference and other alternative signals. And that is why it could matter a little or a lot depending on your situation which USB cable you use.
Or even other USB ‘cleaners’,’filters’, ‘reclockers’ and the like.