A fully-discrete and balanced amplifier audio circuit. The full symmetric dual-mono headphone amplifier with gold-plated 4.4mm balanced connection. Premium engineering is more expensive but lowers the noise floor to a whisper-quiet levels.
Open-back headphones in particular, let all frequencies (especially those precious bass frequencies that the drivers generate so little of) leak freely out of the back instead of trapping and redirecting them back to your ears.
XBass equalisation is a much more elegant solution to bass correction than seen elsewhere. It consists of active and passive components and its frequency response curve corrects their low-end response problems with precision.