I have the Corelli too. Doesn't do much for me.
I brought the Corelli to a friends house and it was very profound in a a bad way.
This device says Piezoelectric stuff inside. So its a inexpensive ground box. I have tried a inexpensive ground box, Putitan. Heard nothing. Others I trust have very positive experiences with ground boxes. Generally ones that suck well over $10,000 from their wallet to fully apply it to the system.
My experience is everyone has noise to some degree. Every system has its own degree of susceptibility to the noise. Some people will therefore hear a large impact from this device. Others nothing. And some maybe hear a negstive impact. I would guess negative would be very infrequent. A ground.box has little reason to make the sound bad. It should be a soak for electrons that seem to float all over the chassis and in the circuit of equipment. Its easy to put a quality true rms meter on the chassis of your gear and measure mV of potential all over the chassis and between chassis. As well as on the ground studs. Its hard to measure a change in these voltage as they are constantly fluctuating.
Every system is different. I have a dozen PS Audio little plug in’s that have a very slight effect. A few ifi plug in’s that I don’t hear a difference. I also have a CAD GC1 and GC3 and those have a profound effect, more than the Corelli’s, but also more expensive.