Two relaxation processes, involving dc conductivity and the glass (alpha) structural relaxation, respectively, were measured in the low-molecular-weight glass-forming liquid, bisphenol- A-propoxylate(1 PO/phenol)diglycidylether, by dielectric spectroscopy, as a function of temperature and pressure. We focused on the correlation between dc conductivity and the alpha-relaxation time, proving that the fractional Debye-Stokes-Einstein relation is valid for both isobaric and isothermal data. The value of the exponent was independent of both temperature and pressure, and related to the ratio of the apparent activation volume of the relaxation processes being considered. The shape of the dielectric loss alpha peak did not change with either temperature or pressure; i.e., frequency-temperature-pressure superposition was valid in the vicinity of the glass transition.