IMO - "classic" (C)LCLC filter after (tube) rectifier has large ripple attenuation and a good regulation, especially that "average" current "draw" from SE amp is a pretty much constant. The most benefit from regulated supply is probably a very low output impedance (rel. high impedance from "classic" supply has influence on sound and even loss of power - PS imp. is in series with output tube). But, is this worth the hassle to build the (tube) regulated supply...hmm?!