Due to their highly refractory nature, the fabrication of fully dense, additive-free, transition metal borides generally requires severe processing conditions. This target is made even more difficult when considering binary to quinary systems, involving multiple metallic elements, given their inherently chemical complexity. For instance, temperatures exceeding 2000°C and long processing times are usually adopted for the obtainment of dense High Entropy Borides (HEBs), a recently discovered class of Ultra-High Temperature Ceramics (UHTCs). In addition, precursors are also often subjected to preliminary treatments, such as intense ball milling, with final products contaminated by milling tools other than oxide impurities. In this work, various binary ((Zr_0.5Hf_0.5)B₂, (Zr_0.5Ta_0.5)B₂) and HE ((Hf_0.2Mo_0.2Nb_0.2Ta_0.2Ti_0.2)B₂, (Hf_0.2Mo_0.2Zr_0.2Ta_0.2Ti_0.2)B₂, (Hf_0.2Zr_0.2Nb_0.2Ta_0.2Ti_0.2)B₂)) borides are successfully obtained as single phases and in bulk form by a two-steps process. Precursors first reacted by Self-propagating High-temperature Synthesis (SHS) route are found to be, depending on the system, highly or moderately converted into the desired phase. In any case, the use of the SHS method is found to significantly promote the obtainment of the single-phase ceramic during the subsequent Spark Plasma Sintering (SPS) stage. The effect of several operating parameters (reaction stoichiometry, ball milling treatment, graphite addition, sintering conditions, etc.) on product characteristics (density, composition, microstructure, etc.) is systematically investigated. In particular, the introduction of small amounts of graphite (0.5-1 wt.%) to the SHS powder prior to SPS is highly beneficial to improve the resulting product density and purity.