Is no preamp really better that a good preamp?

Interestingly, Paul McGowan, designer/manufacturer of the OP's DAC, has just in the past few days been posting thoughts on the very question being discussed here in his blog at the PS Audio site. Some excerpts:

My adamant stance against inserting a preamp between a high quality DAC like DirectStream and the power amplifier should be no surprise to readers of this blog. As well, my subsequent turn around embracing the exact opposite should lift no eyebrows either. But why would inserting an extra piece of gear in the signal path sound better than a more direct approach? How could this make sense? ....

... For a long time I found that DACs with no-loss digital volume controls sounded better, cleaner, livelier, directly into the power amplifier. Whenever I inserted a preamplifier it sounded different–but not better. That is until I tried a different preamp. My first revelation happened with the stunning Aesthetix Calypso preamplifier. Placed between the DAC and power amplifier, music took on a life and dimensionality that took all of 10 seconds to find it was better–not just different....

... I had written earlier that it’s likely I am asking the wrong question. How could adding more to the signal path make the system sound better, not worse? It turns out the logic is correct: it cannot. So why does sometimes adding a preamp between a DAC and power amp help the system sound better?

Because it’s helping the DAC not sound worse. And that bit of logic is key to answering the question....

... Imagine we have a DAC with an identical output circuit to that of a preamplifier. How would this respond driving a power amplifier directly? Theoretically as well as a preamp and, perhaps, better because we haven’t another component in the mix. But here’s something you may not have thought about.

DACs are significantly more sensitive to power supply changes and noises than preamps. When an output stage struggles to drive a complex load, it is the power supply feeding its output stage that sees these changes. If this occurs in a preamp, it has little effect. But that same situation, when applied to a DAC, has very different results indeed. Small changes in power supplies have big impacts on sound quality–especially jitter.

So this is one reason, and there are more, some preamps can help a DAC.

Makes sense to me. So if Paul McGowan can do an about face on this issue, at least under some circumstances, I guess I can too :-) But I believe that in general the opinion I expressed in my first post in this thread still stands:

09-23-15: Almarg
The burden of proof should always be on adding anything to the signal path that is not an obvious necessity. In this specific case a preamp is not an obvious necessity, and per George's analysis (with which I agree) the odds appear to be in favor of that burden not being met. However, as others have indicated the only way to know for sure is to try it.

Regards,
-- Al

I'll go along with that also Al,

1: The dac's power supply for the output stage as PM states is not up to it.

2: If the dac output buffer is not low output impedance <300ohms, as some very weak tube output dac are today some I've seen up to 3000ohms.

3: The impedance load as seen by the dac output is so severe that only something like a Krell preamp's output stage at 1ohm output impedance is able to drive it.

Cheers George

Thanks, George. I suppose an additional possibility is that high frequency noise resulting from a ground loop condition between a DAC and a power amp could enter the DAC's output circuit and find its way via grounds, power supplies, stray capacitances, etc. to the D/A converter device and/or its surrounding circuitry, causing an increase in jitter.

Of course, depending on the specific designs introducing a preamp between the DAC and the power amp could either resolve such a problem, introduce such a problem, or make no difference.

Regards,
-- Al

Many thanks, Al, for the heads up.
When we trust our own ears as PM did, the sound truth is revealed as is.
We also understand a little bit more about the theory behind the listening experience.
Cheers! J.

For most of us who are untrained in electronics, we just go by what has been posted previously in this thread :

"Well, it's all very simple then.
1. Start with no preamp in the chain.
2. Then add preamp.
3. If adding preamp makes the sound better, keep it.
4. If adding preamp makes the sound worse, remove it.
Preamp or no preamp brigades become superfluous very quickly here."