The QUASY project aims to develop innovative concept of X-ray spectroscopy for studying atomic and electronic structures of materials. Current spectrometers face a trade-off between energy resolution and detection efficiency. To overcome this, QUASY will develop magnetic microcalorimeters (MMCs), ultra-sensitive cryogenic detectors with ~1.6 eV resolution, ~100% efficiency, and a broad energy range. Integrating MMCs into the KIT Light Source (KLS) beamlines will enhanced spectroscopic capabilities, enabling higher throughput, multiple-line emission probes, and advanced radionuclide research.