PRat: a DAC or transport thing?

There are many factors that affect a system's PRaT, it is not restricted to the transport and DAC. I'd say that both components are equally important, as is the amplification and cabling (and pretty much everything else in the audio chain).

prat is misunderstood. if you play a cd on two stereo systems, and both cd players are spinning the cd at the same speed, the elapsed time will be the same for each stereo system. thus, the pace must be the same as well as the timing. if one perceives that one stereo system seems "faster" or another "slower", it's in the mind, not the music.

what is it in the presentation that creates the psychoacoustic effect of speed ?

Hello, in theory Mrtennis is right,
however in practice, your 10 yrs old Accuphase transport might
need re-calibration. The main crystal is aging, because of that it could change transport's main clock frequency.
If this change is more than +/-200ppm the rhytm and tempo of music will change. After all sampling frequency (44.1Khz) derived from main clock.

Ahh, Mr. Tennis. You don't understand PRaT, and probably never will until you hear a system that does it well. It is not a matter the speed of a disk, it is a matter of how an entire system reproduces music in a manner that gives a sensation of rythmic tightness, or "pace". It is a very real thing.

Mind you it does come at a cost. Systems that do PRaT well (Naim, Linn) do so somewhat at the expense of other aspects of music reprodution that others may find more important. But to say that there is no such thing because records/CDs spin at the same rate is to completely miss the point. It is even more over simplified (and in error) than saying there is no difference in the sound of cables because they all are transfering the same electronic information from one component to the next.

PRaT and cables all in one message. Next we will have past life regressions and crystal power. Spend your money on something real like room treatments and speakers.