Rectified AC vs switching power supply


2012-03-22 8:37 am
Higher end audio equipment are typically powered like this:

Mains power -> transformer -> rectifier -> filtering circuit with or without regulation

Lower end audio equipment, for cost cost consideration, are often powered like this:

Mains power -> cheap wall wart (mostly switching power supply -> filtering circuit with or without further regulation

I'd imagine, transformer + rectifier would last a lot longer than the typical cheap wall warts. But apart from this, is there any reason that we don't use those to power our low powered audio equipment?

Of course I don't mean that we should feed the output from a switching power supply directly to audio circuitry. With filtering and regulation circuitry in place, is there a reason why switching power supply isn't used more often in low powered DIY builds?

Would it be easier/cheaper to smoothen out lower amplitude high frequency noise from a cheap wall wart than higher amplitude lower frequency noise from rectified AC? Or is it not?

Then, there are higher end switching power supply that has switching frequency well beyond the audio range. How about those?

If people aren't doing it, there might be a good reason. Please educate me. :)