ADSL is the most popularized access technology worldwide. Because it's deployed over the conventional twisted pair telephone network. All DSL systems present a higher effect of crosstalk, which limits its performance considerably. Several research and industry groups have worked on improving DSL's systems performance to exploit the existent copper loop plant, as a previous step of the implementation of full-optical solutions in the access network. In this paper, we present a brief description of ADSL and the system model of DSL technologies that implement a DMT modulation scheme. We also mention the three most important Spectrum Balancing algorithms, which is a kind of methods that improves system's performance finding optimal power spectral density allocations. These algorithms are subject to comparison by a simulation scenario of two ADSL systems. Finally, the results of data rates and power spectral densities are analyzed in order to compare the performance of each algorithm.