Tradition is the main reason you see tube rectifiers in tube power amps. Quite often when that is the case, you will also see that the amplifier circuit itself is from the 1950s or 1960s.
5AR4s have a controlled warmup characteristic, so they do get used in tube circuits to prevent cathode stripping of the power tubes. There really isn't a reason to use one in a preamp. Dan Wright's circuit probably sounded good due to proper design, not the rectifier, and I agree he's done some nice work with his CD player mods. I liked his Oppo mod quite a lot- we used it at AXPONA a few years ago.
5AR4s have a controlled warmup characteristic, so they do get used in tube circuits to prevent cathode stripping of the power tubes. There really isn't a reason to use one in a preamp. Dan Wright's circuit probably sounded good due to proper design, not the rectifier, and I agree he's done some nice work with his CD player mods. I liked his Oppo mod quite a lot- we used it at AXPONA a few years ago.