Is no preamp really better that a good preamp?

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.

Good luck. Regards,
-- Al

A P.S. to my previous post: If you do eventually have an opportunity to try a tube (or other) preamp in your system, and if you find the resulting sonics to be preferable to no preamp, keep in mind the possibility that the root cause MIGHT be a less than optimal tonal match between your power amp and your speakers. Particularly in view of the impedance characteristics of the speakers (4 ohms nominal, 0.8 ohms at 20 kHz), which could conceivably result in an over-emphasis of the upper treble in conjunction with some solid state amplifiers.

Should that ever prove to be the case, changing power amps would probably be a better solution than adding a preamp.

And if there is any uncertainty in that regard, researching reported user experiences involving the use of Spectron amps with Martin Logan speakers may be helpful.

Regards,
-- Al

09-27-15: Georgelofi

Of course Jon2020, and I've said exactly that, if he likes what a preamp adds (and that's a colouration) because something else is not quite right that's ok.

What erks me is when the preamp brigade use blanket statements that preamps are better than direct period, without even knowing if the user needs that colouration or not in his or her system.
And then also saying it drives the poweramp/interconnect better which in this case it cannot, as he has a perfect impedance, voltage and gain match going direct.

IMO George's post is very well put, and I fully agree (assuming, that is, that "erks" is a Down-Underism for "irks" :-)).

I would emphasize the phrase "because something else is not quite right." As I stated earlier:

If you do eventually have an opportunity to try a tube (or other) preamp in your system, and if you find the resulting sonics to be preferable to no preamp, keep in mind the possibility that the root cause MIGHT be a less than optimal tonal match between your power amp and your speakers. Particularly in view of the impedance characteristics of the speakers (4 ohms nominal, 0.8 ohms at 20 kHz), which could conceivably result in an over-emphasis of the upper treble in conjunction with some solid state amplifiers.

Should that ever prove to be the case, changing power amps would probably be a better solution than adding a preamp.

Note that I said "probably." It is also certainly possible that adding a preamp in that circumstance could be a good solution. But my point is that if the sound improves as a result of the addition of a preamp, the possibility that something else should be replaced, instead of the preamp being kept in the system, should be kept in mind.

Best regards,
-- Al

Not to disagree with two of my favorite and most respected A'gon colleagues (Ralph & Jon), but if:

1)The output stage of a source component can drive whatever power amp is being used and the associated interconnect cables without compromise, or, alternatively, at least as well as whatever preamp might be inserted between those components, AND

2)The volume control in the source component, assuming it has one, is EITHER:

(a)As transparent in the range of settings that would be used in the no preamp configuration of the system as it would be if set for use with a preamp (i.e., at or near max in typical cases), OR

(b)As transparent as the volume control that is provided in whatever preamp might be introduced into the signal path,

then it seems to me that the only way inserting a preamp into the signal path can result in sound quality that is subjectively preferable would be by producing an output that is less true to the source material (i.e., less accurate) than the signal that is provided to it by the source component.

And I believe that George is using the term "coloration," or "colouration" in Down-Under speak, to mean essentially the same thing as "inaccuracy."

Best regards,
-- Al

Rustler, with the Calypso I would have the concern I cited in my post dated 9-26-15, that its gain (specified as 29 dB balanced/23 dB unbalanced) may be so high that you may forced to use it with the volume control on the DAC set too low to be optimal. That issue is much less likely to occur with the Capri or Capri S2, which have gain specs of 14 dB.

Aside from that, I don't see any technical issues with either choice.

Good luck. Regards,
-- Al

Regarding the lengthy technically oriented post which Ralph provided yesterday, I of course agree 100%. At the same time, though, I believe his post is not at all inconsistent with mine that preceded it, in which I said:

If:

1)The output stage of a source component can drive whatever power amp is being used and the associated interconnect cables without compromise, or, alternatively, at least as well as whatever preamp might be inserted between those components, AND

2)The volume control in the source component, assuming it has one, is EITHER:

(a)As transparent in the range of settings that would be used in the no preamp configuration of the system as it would be if set for use with a preamp (i.e., at or near max in typical cases), OR

(b)As transparent as the volume control that is provided in whatever preamp might be introduced into the signal path,

then it seems to me that the only way inserting a preamp into the signal path can result in sound quality that is subjectively preferable would be by producing an output that is less true to the source material (i.e., less accurate) than the signal that is provided to it by the source component.

And it would seem, on paper at least, that in the specific case of Rustler's PS Audio DAC both of the criteria I listed above should be met. Essentially, the output section of his DAC **is** a preamp, or so it would seem.

Which means, IMO, that if he finds insertion of a preamp to result in improved sonics, chances are the sonic effects of the preamp would be compensating for an issue elsewhere. Which is not to say that there would be anything necessarily wrong with introducing a preamp as a solution, but the possibility should be considered that changing something else in the system, perhaps the power amp, might be a more optimal solution.

Best regards,
-- Al

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

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

09-26-15: Rustler
I guess my final question, then, is what kinds of specs should I look for in a preamp if I want to add one at some point?

As I've said in some past threads, the main usefulness of specs, IMO, is to allow candidates to be ruled OUT from consideration, based on poor or questionable technical compatibility with the other components in the system, or on the basis of user preferences such as cost, size, weight, appearance, remote control capability, etc.

In this case I believe you are fortunate in that from a technical standpoint it appears that your existing system would be compatible with the vast majority of both tube and solid state preamps. The one slight question mark that occurs to me involves some preamps, such as certain Conrad Johnson models, which provide very high gain (e.g., 25 db or more). Gains in that vicinity, or higher, MIGHT cause you to have to operate the preamp's volume control undesirably close to the bottom of its range if (as would presumably be desirable) the preamp were used with the volume control on the DAC set at or close to the top of its range.

Beyond that, all I can suggest is that you research what kinds of preamps others have reported to provide good sonic results with the same or similar speakers and amplifier. "Similar" meaning, at least, Martin Logan speakers and high powered class D amplifiers.

Good luck. Regards,
-- Al

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