In slopes and embankments, soil elements are often anisotropically loaded and the sustained stress ratio SR may vary a lot. The understanding of the influence of SR on the small-strain shear modulus G0 of sands prior to failure is a practical concern that remains inadequately understood in the existing literature. This study aims to address this knowledge gap through a meticulously designed experimental program. The testing program encompasses three quartz sands with differing particle shapes and a diverse set of principal stress ratios produced via drained triaxial compression. By employing bender elements embedded within the apparatus, elastic shear waves are generated, enabling the measurement of G0 from isotropic stress states to anisotropic stress states. A careful evaluation and comparison of existing anisotropic G0 models in the literature is also conducted, and the potential limitations when subjected to elevated SR levels are noted. A new, unified model is proposed to effectively characterize G0 of different sands subjected to a wide range of triaxial compression states and it is validated using literature data.