Phone preamp question

@dpop 

High quality audio is always directly associated with high quality power supplies.

a very general statement. No offense intended, but I'm not sure a bare bones $250 Bellari phono preamp qualifies as high quality. In this case, switching out power supplies will probably not reveal much. ...

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

In my case I've been using the similarity priced NAD PP2 phono preamp. There is substantial ripple voltage on the included wall wart. I don't have the measurements  handy, but they were disturbingly high for the application. So, I went to my local electronics parts store and bought a nice (over-overkill) 100VA, 28v transformer, a 7824 regulator, 4,700uF 50v and 470uF 100v caps and assembled a dead-quiet 24VDC power supply for the NAD PP2. While at it, I upgraded the power connector to a 2 pin screw-lock type, and replaced the plebeian NE5532 IC op-amp with a Burson SV6 Classic discrete op-amp. The results were quite pleasing to the ears, with the faster slew rate Burson and oodles of clean power at its disposal. 
 

So, yes - a wall wart can be a limiting factor, depending on the application, and the quality (or lack thereof) of the wall wart output. 

@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?