I also picked up an X3 and sold off my SXFI Amp for use on my PC. I haven't had the same problem you mention, though I only use 7.1 with my headphones, not speakers. However, I was having a couple problems with the X3 when it first arrived. It would disconnect upon restarts and I had to continuously reconnect the USB cable to see it again. Occasionally settings would have to be forgotten. I tried a different USB C cable and then everything worked just fine. I contacted Creative and they replaced the cable. I haven't had any problems since.
Regarding this question, I'd say it depends on your main usage. I'm no audiophile, and use the X3 on a pair of Fidelio X2HRs and Sennheiser HD6XXs. In the software you choose the headphone you are using, and it adjusts the headphone gain for you (32-149 ohm or 150-600). I use the X3 mostly for gaming and casual music. You can adjust the SXFI equalizer via your phone or PC software, and I found pairing the X3 with my open back Fidelios gives a very immersive gaming experience. Played a bunch of Modern Warfare and Outer Worlds and enjoyed it. I would think movies with the X3 would be good too. However, this is a "gaming amp". It includes a mic input as well as speaker outputs. You can switch between playing sound via headphones or speakers, and have different EQ settings for both (or "lock" them both to the same EQ settings). If you were only interested in a pure music listening experience, maybe stick with the O2. The advantage of the X3 is the SXFI and EQ modes as well as mic input and switching between speakers/headphones. It may have more features than you care about using, in which case the extra bells and whistles may be useless or distracting.
