He is comparing a s/e 3-ch, one-box Beta against the Rudi amp. The Beta was build by a very high quality builder and is reputed to be excellent and lacking in any hum issues. It was a mostly stock build using amb's recommend parts with a gain of 8 and the e22 backplane board. It uses an Alps RK40 Black Beauty pot, has an extremely well shielded transformer to eliminate any PS induced noise, two switchable inputs, and binding posts for speakers/K1000s on the back panel.
None of the cans you want to use are terribly hard to drive, but are not easy to drive well. I would say based on knowing the RPX-33 pretty well and knowing the Beta sound (I own one) and knowing the builder of the amp in question that the Beta would outshine the Rudi on all of those cans. The only benefit to the Rudi amp is the high and low ohm jacks, but I don't think it has the guts to drive your cans as well as the Beta would. Plus, the price of the Beta is ridiculously low.