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Phono preamps as a class draw almost no electricity, whether in use or idle,so providing a means of depowering them isn\'t an issue. Many of ours have a power indicator so you can tell they are plugged in,but again this is more of a convenience than a needed eature. Many stereo receivers and Amps have a switched AC outlet on their rear which you can plug the preamp into if you want it depowered when not in use. Eliminating the AC cord and moving the power supply out of the preamp itself by utilising an AC adaptor has three major advantages:
A) Separating the power supply physically from the preamp circuitry reduces circuit and AC noise,and improves S/N ratio.
B) The power supply can be replaced in the event of lightning or surge damage without having to replace the entire preamp
C) The preamp can be powered by any clean source capable of generating the proper DC voltage, including batteries or the power supply in an existing piece of quipment, such as a mixer or console used by studios or DJs. Also, the preamp can be used anywhere in the world by simply obtaining a replacement AC adaptor made for the local mains voltage (100VAC, 220VAC, 240VAC,etc) at local shops.
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