Jafox, Gs5556 said, "Generally speaking," implying his awareness of anomalies such as the one you identify. There always have been instances where companies charge more because their brand name recognition allows them to, notwithstanding better quality available from other (perhaps less commercially recognized) manufacturers at comparable (or lower) price points, viz., your example of AR vs. BAT (with which I concur).
To get back to Jpaik's question, besides power supply, other issues significantly affecting cost (other than fit-and-finish and overall build quality) are the nature and quality of the volume control (beyond tube choice, volume control is another way in which many preamps add their own personality, color or even noise) and the quality of the internal wiring (point to point vs. circuit boards, e.g.).
I also add my voice in support of those championing the AI gear. I have owned both L1 and M3 in my time, and both provided outstanding sound and quality for the price, as well as being quite customizable in terms of sonic character with tube rolling.
To get back to Jpaik's question, besides power supply, other issues significantly affecting cost (other than fit-and-finish and overall build quality) are the nature and quality of the volume control (beyond tube choice, volume control is another way in which many preamps add their own personality, color or even noise) and the quality of the internal wiring (point to point vs. circuit boards, e.g.).
I also add my voice in support of those championing the AI gear. I have owned both L1 and M3 in my time, and both provided outstanding sound and quality for the price, as well as being quite customizable in terms of sonic character with tube rolling.