Preamplifier power supply

Yes you do need a good quiet power (toriodal) supply that keeps noise away from the circuitry - and big capicitance like on a big power amp is one way to do that. Of enormous criticality is how power supply is kept away from ground and how balanced the signal lines are designed with respect to ground.However, it can't be simplified to just that.

It is just as important to have features other than just a good power supply - balanced, high output levels with great channel separation and low output impedance and high input imepdance and of course low S/N. High quality tone controls with a "defeat" option for refernce. Volume control needs to be well implemented like with a discrete resistor network steps (like a crystal CS3310 or Burr Brown PGA2310) rather than just a cheap pot and wiper with continuous volume control, IMHO.

for example the built in preamplifier in the Benchmark DAC.

To me it sure looks like a pretty big overkill toroidal transformer in that little box...

I think with saying that a passive preamp is a "terrible mistake" some of us would feel offended (btw, myself not included).

Ooops sorry - good point. However, there is a good reason for OTL designs: transformers are simply not the greatest of devices when it comes to linearity.

Btw, some of the fellow Audiogoners use passive preamps (resistor or transformer based) with NO power supply at all --> do they have poor dynamics and bass response?

This is a terrible mistake. You will not achieve high input impedance and low output impedance with a device like this. In the worst cases the sound will change character audibly with volume as the circuit will act like a filter when it couples with the source and power amp. Remember a preamp is also a "buffer" - it allows the source to see high impedance (making the source have an easy life) while driving the power amp faithfully with whatever it needs - irrespective of small load variations. Buffering and high S/N cannot be achieved without active circuitry. Volume adjustments require around 120 or more decibels of control - it is not a simple task if you want to do it with high channel separation and high S/N and low distortion/transparency.

After 30+ years of listening I now feel that the size of a preamp power supply has no more to do with the sound of the music than the size of the woofer in a speaker.

This might be music to your ears but it is probably even more music to a manufacturer's ears.

Are you really suggesting (as a generalization) that a manufacturer can now use a small cheaper power supply and a small cheaper woofer with small cheaper motor and small cheaper voice coil (often no bigger than a tweeter): And in general it sounds better or just as good (in general no benefit from using better parts)?

I agree there is such as thing as diminishing returns and many reasonably sized but well designed power supplies are adequate for the job but please....this is audiophile heresey! LOL - Just Kidding ;-)

Actually, no, that is not what I'm suggesting at all.

We agree then on that aspect - good.

Do not mistake quantity for quality, they both start with the letter "Q", but are very different.

Sorry, my bad.

Don't confuse smaller with cheaper.

How silly of me.

Are you suggesting that all you can eat buffets offer the best quality food?

Huh? Are you offering to buy me lunch? ;-)

How about the local Chinese buffet?

What you mean the new Mission, Quad, Wharfedale, Tag McLaren and AudioLab speakers?

Or would that be confusing China with cheaper? LOL

Or would that be confusing good food with all you can eat melamine?