Some patience is required with this ground conditioner because it took several days for an improvement in SQ to occur in my system.
When I just plugged the cable in and out of both motherboard USB and JCAT LAN connectors, no immediate difference in SQ occurred and after a few days of trying I was really disappointed (to put it mildly). I actually thought that I’d wasted my money and I was going to return the cable. Just in case I missed a trick, I re-read the information on the JCAT webshop which states that improvements in SQ could take « several days to a week » to happen. Carlos also mentions something similar in his post above. So before returning the cable I thought I’d try leaving it plugged in with the system turned on permanently. About three days later (and without enthusiasm) I went back to have a listen. I must admit I was surprised because the SQ was more natural and analog. I’d never heard my system sounding this good before! Wow. How is this possible?
The improvement in SQ was so significant (especially on timbres, treble and voices which became more airy and spacious) that since it's become impossible to remove the ground conditioner. If the PC is turned off for just a short while, the beneficial effects of the cable on SQ are still preserved when the PC is turned on again which is cool.
This cable is a key part of my setup from now on and despite a bad start, I’m pleased that I figured out how to use it. Some guidance about this could have saved me time, but perhaps it’s understandable for a new type of product. My initial dismay has turned into listening joy and I’m rediscovering my albums once again. Hopefully this experience will help others. Thank you so much Marcin for this truly remarkable cable, although it must be used with the PC turned on all the time. Regards.