No, don't do this. You'll be feeding single rail 24v DC as well as additional dual rail 24v DC to the pre-amp and you may cause damage.
Naim's reasoning for routing the signal through the pre-amp PSU:
The absolute earth reference for the system is the reference for the pre-amp, which is the SUPER-CAP, HI-CAP or FLAT-CAP earth. The signal is routed from the pre-amp to the power supply using the same interconnect that takes the power feed from the power supply to the pre-amp. It also connects the two earths together.
This minimises differential voltages caused by interfering electric or magnetic fields being generated between the power feed, signal and earth, so maintaining the correct relationship between signal and earth inside the power supply. The power amp is connected to the properly referenced signal at the power supply output.
And, if you're worried about any possible "interference" between the power supply and the audio signals:
The DC power feeds passing through the SNAIC contain virtually no AC components. Since only AC can be coupled to adjacent conductors in the cable, the power feeds cannot interfere with the audio signal. The supplies also have minimal source impedance (less than 0.1 Ohm) and this prevents supply modulation by the very small signal currents.
