@gaetan The sound glitches were the most noticeable. It was a weird crackling. Sadly I only have three DC games on the system (Souldcalibur, MvC2 and Virtua Tennis). VT had graphic glitched on both settings and MvC2 produced blank vertical lines through the sprites when they moved to the right side of the screen in CEA. It was a weird effect (and only on some sprites... A wild guess is that they used textures over flat 3D models instead of sprite hardware here, but that's really just speculation.

@Huey-Le
If you use following shader, no pixels anymore. I use it globally.

/recalbox/share_init/shaders/shaders_glsl/scalehq/2xScaleHQ.glslp