S.M.S.L PO100, PO100 PRO & PO100 AK - Measurements (Digital Interfaces & DAC)

[Witterings]

You can control volume in the digital domain (i.e. via the phone), but doing it this way reduces dynamic range.

Is that the same with a PC do you know and in which case I guess I should set the PC to 100% volume ?

 

[Pearljam5000]

You can control volume in the digital domain (i.e. via the phone), but doing it this way reduces dynamic range.

So how can you control the volume without reducing the dynamic range?

 

[Ted B]

Is that the same with a PC do you know and in which case I guess I should set the PC to 100% volume ?

It is typically not a problem to make nominal reductions in volume this way when using a PC to feed a DAC, but large reductions may have an audible impact. If you have a means of controlling the volume further downstream, I would set the PC's digital output volume at around 95%, just to create a small buffer such as not to overdrive the DAC, and control volume either at the DAC or in the analog domain.

So how can you control the volume without reducing the dynamic range?

The easiest answer is control it in the analog domain, for example, with a preamp placed between DAC and amplifier or the gain (volume) controls of an amplifier. Modern DACs with an onboard (digital) volume control may use upsampling to mitigate the effect. If the DAC is in powered monitors and you are using a phone as a source, I would adjust the speaker volume controls (assuming they are present) such that the volume setting of my phone app was close to maximum at typical listening levels.

 

[jacobacci]

Sorry if this was mentioned somewhere in this thread. Does the PO100 work with a USB-C iPhone or iPad connected directly (without inserting a powered USB hub)?

 

[Oukkidoukki]

Sorry if this was mentioned somewhere in this thread. Does the PO100 work with a USB-C iPhone or iPad connected directly (without inserting a powered USB hub)?

Yes

 

[Pearljam5000]

Is the PO100 PRO better than these?

 

[Roland68]

View attachment 500211View attachment 500212
Is the PO100 PRO better than these?

I'm not familiar with the U2, but the U2Pro delivers similarly good results to the PO100 Pro. In a simple comparison, I couldn't detect any difference.
If you don't need the i2s over LVDS interface—which is generally a worse connection option than SPDIF for most DACs anyway—then take a look at the PO100 AK. For a small additional cost, you also get a good DAC based on the AK4493.
However, the PO100 AK cannot be switched to UAC1 if needed.

 

[jimmy_WAI]

The size advantage of PO100

 

[Descartes]

Yes

Just ordered one looking forward to seeing well it works!

 

[Curdrone]

I have been using the PO100 Pro for quite some time now and can only recommend it to a limited extent.
There are no problems with low quality (AAC/MP3 radio streams). But a Qobuz subscription quickly revealed the limitations of this device.
As long as you listen to the same quality, everything is fine, even up to 24-bit/192 kHz.
However, if you have a playlist with frequently changing quality, there are often disruptions (distortion, dropouts, regular crackling) when transitioning to higher quality (24-bit/48 kHz and above).
You then have to pause playback and restart to fix the problem. In my opinion, things like this should not happen.

 

[Descartes]

I have been using the PO100 Pro for quite some time now and can only recommend it to a limited extent.
There are no problems with low quality (AAC/MP3 radio streams). But a Qobuz subscription quickly revealed the limitations of this device.
As long as you listen to the same quality, everything is fine, even up to 24-bit/192 kHz.
However, if you have a playlist with frequently changing quality, there are often disruptions (distortion, dropouts, regular crackling) when transitioning to higher quality (24-bit/48 kHz and above).
You then have to pause playback and restart to fix the problem. In my opinion, things like this should not happen.

That’s unfortunate my playlist from Apple Music has a great variety of quality from lossless to Hi-Res we will see if I get the same problem with my iPad

 

[Pearljam5000]

Which model of the PO100 is the best one?

 

[Roland68]

Which model of the PO100 is the best one?

The best for what?
The old PO100 is no longer available; the current model is the PO100 2024.
The other two PO100 models differ only in their connections. The Pro has an additional I2S (over LVDS) connection, while the AK has an additional DAC (AK4493).
The USB section of all three models is based on the modern XMOS XU316 chip.

 

[antcollinet]

I have been using the PO100 Pro for quite some time now and can only recommend it to a limited extent.
There are no problems with low quality (AAC/MP3 radio streams). But a Qobuz subscription quickly revealed the limitations of this device.
As long as you listen to the same quality, everything is fine, even up to 24-bit/192 kHz.
However, if you have a playlist with frequently changing quality, there are often disruptions (distortion, dropouts, regular crackling) when transitioning to higher quality (24-bit/48 kHz and above).
You then have to pause playback and restart to fix the problem. In my opinion, things like this should not happen.

Is this a problem of the PO100, or whatever DAC it is feeding?

EDIT - either way the solution is generally simple. Just have whatever is doing the streaming resample to a fixed resolution. Redbook will be fine, but if you are of the opinion that higher res is valuable (it really isn't) just have everything resampled to 24/96.

And just to head of any objections of "... but bit perfect..." resampling does nothing audible to the music, unless the resampler is broken.

 

[Curdrone]

Is this a problem of the PO100, or whatever DAC it is feeding?

The PO100 Pro connects my PC optically to a Wiim Amp Pro.
With Qobuz Connect (Ethernet/LAN cable), such interference does not occur, so I think it's safe to say that it's due to the PO100 Pro.
I also tested another (supposedly higher-quality) optical cable, but it made no difference.
Incidentally, problems can also occur with consistent quality when fast-forwarding and rewinding or jumping back and forth between tracks in the playlist.

 

[Pearljam5000]

Is it worth waiting for them or is the PO100 better?

 

[Curdrone]

EDIT - either way the solution is generally simple. Just have whatever is doing the streaming resample to a fixed resolution. Redbook will be fine, but if you are of the opinion that higher res is valuable (it really isn't) just have everything resampled to 24/96.

I'll have to try that out. Is it enough to set the maximum playback quality to 24/96 or 16/44.1 in the Qobuz settings, or do you have to take other steps to achieve the best possible technical results?

Can any Douk Audio U2 Pro users tell me whether this device is prone to the kind of interference I described?

 

[Oukkidoukki]

Just ordered one looking forward to seeing well it works!

It will be great!

 

[antcollinet]

I'll have to try that out. Is it enough to set the maximum playback quality to 24/96 or 16/44.1 in the Qobuz settings, or do you have to take other steps to achieve the best possible technical results?

Can any Douk Audio U2 Pro users tell me whether this device is prone to the kind of interference I described?

Best to set your PC to always output whatever sample rate you want regardless of source. I use a mac and know how to do it there.

Not so sure on windows. Im sure someone will be able to chime in.

 

[Descartes]

The best for what?
The old PO100 is no longer available; the current model is the PO100 2024.
The other two PO100 models differ only in their connections. The Pro has an additional I2S (over LVDS) connection, while the AK has an additional DAC (AK4493).
The USB section of all three models is based on the modern XMOS XU316 chip.

So they should all sound the same, I like the smaller form factor for the P100