This contribution presents the 3D Tune-In (3DTI) Toolkit, an open source C++ library for binaural spatialisation which includes hearing loss and hearing aid emulators. Binaural spatialisation is performed through convolution with user-imported Head Related Transfer Functions (HRTFs) and Binaural Room Impulse Responses (BRIRs), including additional functionalities such as near- and far-field source simulation, customisation of Interaural Time Differences (ITDs), and Ambisonic-based binaural reverberation. Hearing loss is simulated through gammatone filters and multiband expanders/compressors, including advanced non-linear features such as frequency smearing and temporal distortion. A generalised hearing aid simulator is also included, with functionalities such as dynamic equalisation, calibration from user-inputted audiograms, and directional processing.