An energy minimization and balancing approach was adopted to predict the occurrence of spike noise by obtaining estimates of the magnetostatic and total wall energy of a soft underlayer (SUL) for a given configuration of domain walls. We find that single-layer SULs (thicknesses of 100-200 nm) are usually sources of spike noise unless their saturation magnetization is below 70-100 emucc. However, the use of such low-moment SULs is unacceptable in perpendicular recording. One solution that has been advocated is a multilayer SUL structure with C, Ta, etc., interlayers. Our predictions show that the ground state of a 200-nm double-layer FeCoC SUL is completely spike-free.