A common misconception is that ARM's power efficiency makes linear power supply design straightforward, while x86's higher power consumption renders it unsuitable for linear power designs.

In fact, a turning point emerged with the release of dual-core ARM processors. Some ARM manufacturers began bundling PMICs (Power Management Integrated Circuits) with their processors, with the PMIC uniformly managing all voltage rails and power-on sequencing. Here is a key concept — power-on sequencing. What is power-on sequencing? It means voltage rail A must stabilize X milliseconds before voltage rail B, and voltage rail B must stabilize Y milliseconds before voltage rail C. For example, memory operating at 1.5V must power on at least 100ms before the CPU at 0.9V, or the CPU will fail to boot because it cannot detect the memory. Since ARM systems incorporate not only memory but also external storage, ADC, DAC, and numerous functional modules — each with different power-on sequencing requirements — this management becomes extraordinarily complex. As ARM CPU core counts, interface counts, and interface types proliferate, power-on sequencing grows exponentially more intricate. Since only the original ARM manufacturers fully understand their processors' power-on sequencing requirements, they launched PMIC bundling to reduce development difficulty for their partners and increase their own revenue. The emergence of PMICs effectively solved this complexity, and using the original manufacturer's PMIC has become the de facto standard.

As ARM core counts increase and performance improves, required operating currents also grow larger. Starting from quad-core ARM, CPU power supply adopts switching power supply to address the contradiction between increased CPU power supply current and surging heat output from core count growth. Currently, industry solutions all use PMIC's built-in switching power supply to power CPU, memory and numerous circuits that significantly impact sound. Therefore, after 4 cores, ARM using PMIC almost has no possibility of being designed with full linear power supply. Of course, PMIC internally still contains a small amount of linear power supply, but these linear power supplies have minimal impact on HiFi design.

To simplify power-on sequencing design, ARM designs typically use passive crystals that can be directly controlled by the processor. As is well understood in digital audio, clock signal quality is a critical determinant of playback performance in HiFi network devices. High-quality, unified-source clocks elevate the sonic ceiling. Replacing passive crystals with high-quality, unified-source clocks is therefore the superior approach.