This paper describes several power mask designs for local loop multcarrier transmission. The proposed algorithms exploit the signal to noise and interference ratio knowledge at the transmitter in order to maximize the overall bit rate. This design prevents from the multiple large constellations soft-demapping burden by using a single mid-size Quadrature Amplitude Modulation (QAM). We illustrate the algorithms performance by giving results for Very high bit rate Digital Suscriber Line (VDSL) systems.