For the purist audiophile though, I would guess its mainly the less stray flux and noise that they are after. From practical stand point, if physical size and weight are important I would pay a little more to get a good quality toroidal. The funny thing is, of all the gear I have, its the EI ones that are the quietest. However, among my 4 Marantz (pre and power) amps, the two with the toroidal are at least quieter than the other two that have the EIs.