DACs are usually twin-ax, which is just 2 coax cables bundled. The shielding matters a lot, compared to unshielded twisted pairs. Faster parallel DACs require

DACs are usually twin-ax, which is just 2 coax cables bundled. The shielding matters a lot, compared to unshielded twisted pairs. Faster parallel DACs require more pairs of coax, and thus are thicker and more expensive.