Good question. My wish, were I to have one, is that someone with extremely precise measurement equipment would measure the difference in the digital output of a $500 streamer and a $3000 streamer (throw out the very cheap and ultra expensive streamers). This would at least let us know if there is ANY difference in the streams and if this small difference would not be retimed/clock accurately by the DAC. I bet I have heard/read 100 times why expensive streamers sound better, but I have never been presented with any evidence from a scope or other precise measurement equipment.

I don’t care if one is better or worse beyond wanting to buy the one that sounds better. Of course, the best option is to blind test both in your system with your speaker/amp/ears.

There is no difference, except in how you hook your streamer to your DAC. Read up, but optical and coaxial can cause slight issues with timing. Whereas usb leaves the DAC to control that, so you would always get the same result.

So the sound depends more on the quality of your DAC for usb, but for optical and coaxial the ‘quality’ of the streamer can have a little impact on the output. But only a little.

The quality of your source (lossless etc.) and the mix of your source (well produced or not?) makes way way more difference.

If you take a bunch of different streamers, whether those are super expensive audiophile ones or a cheap Raspberry Pi, and you hook them up to an external DAC then there will be zero audible difference.

The difference is in the power supply. How well it is isolated from the digital components.

I compared 6 streamers when I was in the market. Used as a Pure streamer only some with DACs and some without.

All were fed to an external DAC. There are noticeable differences to soundstage and details.

It’s noise and interference externally and internally. Along with engineering and design of the components used.

I have to use a Dac with my computer because the build in dac is so bad about this stuff, the noise floor is absolutely terrible, the interference is at disgusting levels.

It’s about the quality of the components and the engineering of the components.

The worst engineers can use the best components and make the biggest pos.

And the best engineers can use the worst components and make something actually pretty nice.

If you’re using a DAC that is transparent, the only difference between analog and digital is interference, range of cables, and latency. Digital being immune to interference, having longer cable range in general, but having at least some small latency where analog does not.

I don’t know what you’re talking about when you say “streamers having different sound if using as a digital transport only”. Do you mean you’ve seen some streamer who switches between and they sound different? Or did you mean to say streams not streamers? Does “if using as a digital transport only” mean you’re asking about the pure difference between analog transport and digital transport, or is the word “as” not supposed to be there?

If hooked up to an external DAC

It doesn’t matter that the DAC is external.

and all it does is transporting 1s and 0s digitally,

That’s not what a DAC does. A DAC converts digital audio formats to analog audio waveforms.

how can that affect Soundstage,

Zero effect, just from “being digital” or “being a DAC”.

how punchy the bass is

Zero effect, just from “being digital” or “being a DAC”.

, etc?

DACs can occasionally drop a sample if clock rates are not aligned.

I have personally done loopback tests on my (designed to be transparent) hardware, where I recorded an output back into an input and compared the resulting samples, to find they were identical.

Now, some DACs are not transparent. The designer can choose to color the sound in some way they think will sound pleasant. There are also desirable features like loudness compensation that can be done at the last preamp stage, which sometimes is the DAC. Also, home theater receivers are DACs and do a ton of processing to adapt the surround arrangement of the content to the actual surround arrangement you have installed, for example “phantom center” to use front L/R in place of a missing center channel, stereo expansion like Dolby Surround, and DSP effects to add artificial room ambiance over music.

If you want to talk about that stuff though, you have to be more specific.

-Power Supply inside the unit

-cheap parts/internal clocking

-the cable going to the Dac

I think there are enough variables that spending more on a good unit is money well spent, it would be the same as a cd player that you connect to a Dac

There is no actual science, just a bunch of different narratives pushed by manufacturers and marketers and propagated by audiophiles.

Some say digital audio transmission is inherently lossy, but it can be verified this is not the case.

Some say it’s about the jitter, but it can be shown that jitter levels are reduced to negligible terms in modern hardware.

Some say it’s about what kind of noise or interference the streamer hardware induces on the system. There may be some truth to this but only under certain circumstances.

Well, it shouldn’t affect anything. Even basic DACs these days should be good enough to achieve transparency. Words like soundstage, punchy bass, etc. mean little to nothing. It is either measurable as changes in frequency response, harmonic distortion, or something such that is actually quantifiable, or it is probably just pure placebo.

This largely depends on the DAC and the amount of jitter that the DAC sees on it’s (clock) source. Jitter is the timing deviation in a digital or clock signal. It’s not only about 1’s and 0’s, it’s about when they arrive and if the DAC’s internal clocking circuitry has the “time” to correct or ignore this timing inconsistency. A DAC chip that is fed a jittery clock source has higher distortion. This can definitely be measured and perceived.

Digital audio signals such as SPDIF or AES-EBU carry both the timing and data information. Conceptually, you could hook up a DAC with a separate wordlock generator (if it has that feature). In this scenario, jitter of the source device (considering it’s also locked to the same wordclock) is now irrelevant and as long as the data signal comes in a timely manner, the DAC’s operating quality will be solely dependent on the jitter of the wordclock generator. The source is effectively only sending data, not timing information.

In practice most modern DACs have a very stable internal clock generator that gets locked to a wordclock or AES/SPDIF clock source in a very forgiving manner. In other words, a good DAC is not affected by jitter and performs at the same level of distortion regardless of clock source. In a lower quality DAC differences of the connected source could theoretically be perceived in the same manner that the same DAC may operate when connected to a jittery clock.

With USB-audio things get more complicated, but I think you’re mostly interested in the concept of why a digital source may matter for sound reproduction quality rather than the exact details.

The digital transport is just one part of the equation. There are long analog signal chains before anything reaches the ADC including microphones which vary wildly in how they transform sound waves into analog signals on a wire. Then the digital transport usually uses compression which can change audio audibly depending on the bit rate. Then the opposite of the ADC chain happens at the DAC side of things. The thinking that “it’s digital so nothing changes” is far too simplistic.

People can train themselves to perceive various sounds in the presence of non-aural cues. It can even survive blind testing in cases where the cues are not visual. So it is perfectly plausible that enthusiasts of expensive DACs perceive better soundstage and punchier bass with different transports.

What is not plausible is that people can identify from listening alone differences in sounds that are below audibility thresholds. A conventional DAC receiving the same 1s and 0s from two different transports is going to create the same sound field. Our enthusiast of expensive DACs may genuinely perceive different sounds from the two transports but they won’t be able to correctly identify from listening alone which is which.

If the expensive DAC enthusiast knows that one or the other is being played the difference in perceived sound may even persist in a blind test with the brain locking onto one or the other sound. It is more usual for an enthusiast that has trained themselves to hear different sound in response to different non-aural cues to become confused but this is not always the case.

Here is an example of audiophile Mike Lavigne reporting his experience in a blind test after training himself to hear differences between two cables. It is very rare an audiophile is prepared to do something like this publicly so hats off to him.