Is no preamp really better that a good preamp?

The correct answer is no. That should suffice for now. Even attenuated power amps with dials for gain like my McIntosh must have circuits that allows for attenuation to control volume is indeed acting just like a passive pre amp.

The correct answer is no! once again.

There might be more to the "impedance matching" than is obvious. A lot of amps have a DC block capacitor at their input, which attenuates low frequencies with a starting frequency that varies inversely with the driving impedance. IOW, with a high driving impedance, the blocking capacitor lets more ultra-low stuff through (which might be good or bad depending.... some amps and speakers need to keep that stuff out).
I use a series cap as a first-order highpass filter to cross to a sub, and a 'passive' box would move the crossover point all over the place.

I am at RMAF and saw the bespoke passive preamp that George posted the link to. It is quite a piece of art, has very smooth input selection and 47 step volume control, and both balanced and RCA connections. Unfortunately cannot judge the sound because it was only on a table display. Based on the view under the hood I can say it is well manufactured with proprietary wound transformers but at the price point it sure makes me pleased I own high value passives like the Lightspeed and Slagle AVC.

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."

Clio9,
I believe you have experienced a TVC before. I did read the review about the Bespoke TVC in Stereophile this month. If anything, I think it was a waste - giving the TVC to a reviewer who already has a biase against "passives". I got a $4k preamp home to see what I am missing against my TVC. And to my surprise, I found my TVC superior to the active preamp. I am sure you are aware that TVC will work only with a matching system. You cannot have an amp/source/speakers that are low in sensitivity.
I will sure seek out to other active preamps in future, when I get a chance, but I agree that the lesser the "electronics" in the chain, the lesser the distortion of the original music. Some folks will opt for color over originality.

"Some folks will opt for color over originality."
Not so - not PM or a whole lot of many others. It all boils down to whether there is an improvement in the listening experience.

Fully agree with Almarg :-
"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."

Can we thank Almarg for finding that interesting bit of information?, yes we can. It is good to know that a preamp still has its uses. Some of you have been corrected, don't need to mention names but you are forgiven.

I also will stand corrected that an active preamp may help if, the source (dac/cdp) has a power-supply problem in it's analogue stage(as PM states) not by just adding colouration, or as I have mentioned it's output stage/impedance and output voltage is not up to the task.

For myself if we have this kind of source with these types of problems that has a VC, I can't think of it being hi-end or been designed right, better to me to change it, mod it for something that is.
How can an audiophile live with his/her source knowing the analogue power-supply stage is not doing it's job (as PM states)

PM... 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.PM

Cheers George

The suggestion then is for PM to redesign his DirectStream such that it sounds better direct to power amp, without need for the Aesthetix Calypso preamp? Poor PM - just to please some dogmatic.....

If you read carefully, not once did he refer the analogue power supply problem to his own PS Audio DirectStream DAC.

I found that DACs with no-loss digital volume controls

Cheers George

If the DirectStream sounds better via the Aesthetix Calypso, the design must be flawed right from the outset?

"For myself if we have this kind of source with these types of problems that has a VC, I can't think of it being hi-end or been designed right, better to me to change it, mod it for something that is."

So, should the DirectStream be redesigned?

Like I said it's all in his careful wording if you read it again, his does not incriminate his own PS Audio DirectStream Dac as having the problem, and I very much doubt he ever will.

He says DAC's, and singles out their power supplies and jitter as the problem, and for all we know he could mean those tiny portable dacs that run on external smp wall wart power supplies.

I still wonder how this one Aesthetix preamp could fix those specific areas he's has singled out.

Cheers George

"I still wonder how this one Aesthetix preamp could fix those specific areas he's has singled out."

We can all wonder but this little gem from PM will get a lot of DirectStream owners to start adding the Calypso to their systems or replacing their current preamps with it, instead of retiring the Directstream altogether.
Why not, if it sounds as stunning as PM describes? Again, theory aside, of course.

Cheers! J.

Better yet, DirectStream owners can wait for the upcoming BHK preamp.

http://parttimeaudiophile.com/2015/10/05/rmaf-2015-its-always-sunny-at-ps-audio/

"Upcoming PS Audio BHK preamp??"

Now that explains things.

Cheers George

....which still does not explain how the Aesthetix could fix the DirectStream's 'problems' and,
....that rather than tout another brand, build one of your own.
The synergy is now complete.

Cheers! J.

An excerpt from today's blog post by Mr. McGowan on the same subject:

Our newest DAC, DirectStream, ... has zero loss at any level setting–a major achievement. So, how could a control with zero resolution be suspect? That’s a question I have been mulling on for some time now.

One piece of the puzzle seems obvious. We know that tiny changes in the way internal FPGA process are organized make significant differences in sound. Even changes to the display affect sound quality. It’s a delicate process when jitter, power supply and the tiniest of changes can be heard and must be attended to. What’s to stop us from believing that different level settings have different sound qualities–despite the fact there are no measurable resolution losses?

Were it to be found true much would be explained. For instance, we know not all preamps sound better than DACs directly into power amps. In fact, most don’t. This observation lends credibility to the explanation that it is not preamps that make DACs sound better, rather, it is preamps helping DACs not sound worse. This theory can only be true if the preamp is of sufficient quality to add less degradation than using the DAC’s volume control. That all kind of makes sense.

But, just because something makes sense, doesn’t mean it’s true. How do we make this determination to see if this theory holds water?

Regards,
-- Al

Milpai, I have had a TVC using S&B transformers and now have an autoformer unit. As you know I am a fan of passive preamps in general and also own George's Lightspeed. They are all a bit finicky to work with but in the right system are great devices. I have been fortunate to have such a system.

However, a couple years ago I found the need for more gain in my system due to my increased use of analog vinyl and tape sources. So I turned to an active preamp for that purpose, and in my case one that is quite transparent. I still use my Lightspeed in a digital system I have set up, where it works flawlessly.

In Mr BHK's own words :-

"As obvious as it may seem, I would like to hear his take on why his preamp improves the sound in comparison to running the DS direct.  I know some still prefer a preamp, I personally don't, but there is some interaction going on that no one seems to clearly understand.  I know Paul had his socks knocked off in comparison to his reference preamp, but my socks are generally well attached and not subject to such easy removal.  In other words call me an agnostic waiting for the right explanation to shift me into belief." -Pmotz

"Hi Pmotz.
You bring up a good point and rather timely as I have been listening to my Direct Stream DAC direct into my power amp as I take my ptototype BHK Signature preamp (1 or 3) in and out of my system to go work on it in my lab.  The system without the preamp in it sounds very nice and acceptable but when the preamp is back in there is a very obvious increase in musicality, transient attack, spaciousness, and detail.  I am amazed and delighted with this creation.  But I must disappoint as I must be in the camp of those who cannot explain it. I just know what it does for my musical enjoyment and that, in the end, is where it is at for me." - BHK

http://www.psaudio.com/forum/bhk-power-and-pre-amp-forum/bascoms-preamp-chronicles/

"For myself if we have this kind of source with these types of problems that has a VC, I can't think of it being hi-end or been designed right, better to me to change it, mod it for something that is."

RMAF 2015 award for best DAC goes to....

http://www.stereophile.com/content/rocky-mountain-international-hifi-press-awards#dUsWps4IBGMLTqEi.97

....the PS Audio DS.