Phone preamp question

@sleepwalker65

I’m in agreement with the notion that a wall wart will almost always be inferior to a well-designed power supply.

I hear ya, but there are also those out there that make the argument that SMPS’ do a great job of isolating 60 Hz hum.

AUDIO MYTH - "SWITCHING POWER SUPPLIES ARE NOISY"

I don’t know if you’ve ever heard the Benchmark amp mentioned in the article, with your own ears, but I have, and to my ears, it is drop-dead amazing, with a distortion figure of 0.00016%. I think I saw a S/N ratio figure of -130 dB. Most audio manufacturers cannot even approach that. Some people prefer the harmonics of tubes. I love the sound of them too, but give me low distortion any day over tubes. If you ever get the chance to hear the Benchmark amp at CES, or a local audio show; definitely make it a priority.

Welp, SMPS are generally capable of producing more objectionable (irritating) noise than the 120Hz-ish ripple from a rectified 60Hz mains supply, but the economics and physical scale are in the favour of SMPS. Having said that, the manufacturing quality and sourcing of most SMPS wall warts and many SMPS modules is sketchy at best. 

@corelli ,

Thank you also for that tidbit about powering it up before the amp.

Ughhh! There is no such thing as a "passive preamp". The two words are mutually exclusive,

Sorry @sleepwalker65 , going to have to disagree with you on that one!

Anybody know if Amperex makes a 12ax7(ecc83) version of their 12au7/7316?

Here ya go!