Difference between "S" headphones and "X" headphones

The S-family of headphones (S3m, S4, S4i, S4A) will utilize dynamic moving-coil drivers (similar to your typical speaker woofers), while the X-family of headphones (X4i, X7i, X11i) will utilize balanced armatures.

So how do you decide what’s best for you?

• If you’re in the mood for a full soundstage and thumping but tight bass, and you’re on somewhat of a budget, we recommend the S-family.
• If you’re looking for clear, crisp, impeccable detail with warmth in the lower octaves like you’ve never heard before, the X-family might be more your cup of tea.