24/11/2017:
Purchased (Black Friday)
23/12/2019:
After two years since I bought them for 100 euros, they are quite decent and powerful speakers, and I haven't encountered any problems (so far). The power supply is filtered by an APC, and the green input of the speaker is also filtered for any interference. The potentiometer has negligible interference. After two years of use, I can say they have settled in as speakers; of course, their bass is quite strong even at the first level (where it "locks"), resulting in it becoming annoying. I don't know much about sound, but I suspect that with a sound card better than the one on your motherboard, you will find the perfect balance. I am more than satisfied. Highs, mids, lows—all very nice, rich sound without distortions. THX knew who to collaborate with and put their signature on it. Well done! One negative thing that I am sure happened to me is that when I lower the volume too much, the sound only comes from the speaker that DOES NOT have the potentiometers and the switch; however, as soon as I raise the volume a bit, everything is fine.
6/4/2020:
After a bit of searching on the internet, I read that the RCA => 3.5mm jack cable is slightly better. Switching to a simple jack with (two obviously) male RCA plugs changed the sound for the better, and the interference was almost eliminated! I am approaching 3 years and I am extremely satisfied!
Searching today 18/4/2020, I found something I had noticed for a while. The speaker with one button and two potentiometers exhibits a scratching sound, and generally when I turn up the volume (this sound does not occur in the bass potentiometer) or if I keep it steady for a while and then turn left or right. After looking into the issue a bit more, I read that the Z623s often have this problem with the potentiometer for adjusting the sound volume. I solved (probably temporarily, time will tell) my problem simply by removing the plastic cover for the potentiometer and spraying a little WD-40 inside, and the scratching disappeared completely; it is even better to spray with contact cleaner. This happens because the potentiometer is analog and not digital, so it collects dust, hence the scratching/interference. This is what I read, and this is what I pass on to you. You can look into it yourself. Nevertheless, I still remain 101% satisfied!
21/11/2020:
Three years now, and everything is as it was on the first day, crystal clear sound just like the first moment. Everything flows exceptionally. I continue to be fully satisfied with this system. If you find them for 90-100 euros (new, of course), buy them.
16/06/21:
Everything is perfect as on the first day, whether highs, mids, or lows!
24/01/22:
Everything is excellent.
24/09/23:
We continue steadily with quality, no problems!
20/11/23:
One potentiometer (the volume one) broke, any repair/replacement is futile. Six years in my hands and they have gone through all stages of metal music, Pontic music, and abundant house music in all its glory. I bought them for 100€; were they worth the money? OF COURSE, an amazing system. What I can say is that it has very strong bass. I am seriously considering buying them again... Very beautiful and warm sound, they have settled in more and more over time. I am completely satisfied!