I never used Realtek. But I think G6 sounds better than ZxR. I suppose ZxR should be better than Realtek, which makes G6 better than Realtek I guess. However, G6 doesn't really have multichannel output (Dolby Digital or DTS). Therefore, I use G6 for music and ZxR for gaming. I bought G6 for portability, which can be used with a laptop and mini PC. Also, I never used high impedance headphones. I have SONY MDR-7520, MDR-7550, and Audeze LCD-MX4, all used on low volume (~40) and low gain.