SMSL PO100 PRO Review (Digital Interface)

[Stoutblock]

I have multiple USB sources but only one USB input on my DAC so I have been using one to convert one source to SPDIF for a seperate input to my DAC. I am happy to say I have had no issues for a couple years now and the converted source sounds the same as before. Neat little box.

 

[Reddy]

The measurements presented here successfully confirm the device's bit-perfect data integrity and low frequency deviation under static lab conditions. However, evaluating a DDC solely via a digital bit-stream overlay or a static J-Test leaves a fundamental blind spot regarding actual signal emission quality under dynamic workloads.
A standard 1 kHz tone or the repetitive patterns of a J-Test draw a highly predictable, periodic current. In reality, actual music signals force the XMOS processor and the high-speed line drivers (like LVDS) into chaotic, non-periodic switching states. Because these digital blocks share a common 3.3V supply rail with the master clock in stock topology, these transient current spikes induce data-dependent voltage fluctuations directly at the oscillator's VDD decoupling capacitors.
Through AM-to-PM noise conversion (as mathematically defined by Hajimiri’s Impulse Sensitivity Function), this power supply ripple translates directly into near-carrier phase noise. This is known as Power Supply Induced Jitter (PSIJ).
A static digital loopback test is fundamentally blind to PSIJ because it only checks if the bits arrive, not when they arrive in the sub-picosecond time domain. Furthermore, evaluating this at the analog output of a modern DAC masks the issue, as the DAC’s internal DPLL constantly works to correct these phase variations. While the AP analyzer shows a clean averaged plot, the continuous corrections in the DAC's clock-recovery loop can degrade transient response and spatial imaging.
To truly expose the performance of a DDC hardware layout, we should not just look at static bit-perfection. The definitive test would be a dedicated phase noise measurement of the clock rail itself while the device is processing a high-crest-factor, multi-tone signal.

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[OldManMatt]

I had purchased one of these last year just for personal subjective listening experiments. More so of the I2s connection.

I did not even try the SMSL at all with my ref RME but did try it with an R2R (Pontus 15th)

I understand that subjective thoughts don't hold weight here but my perceptions of putting the SMSL in the chain wasn't positive long term. I returned the unit & haven't had a 2nd thought about DDC's since. I was using a dedicated streamer as the source.

Should I not have been perceiving a negligible effect to performance..or even any effect at all?

 

[AndyBell]

Should I not have been perceiving a negligible effect to performance..or even any effect at all?

I’ll give the standard reply - unless you did a blind, level matched test then you can’t be certain you perceived anything audio-wise at all.

That doesn’t mean you aren’t sincere in your belief that it sounded different - it’s just that there are so many factors involved, including human cognitive biases, that without such tests, or some measurements, your perception doesn’t in itself hold much weight.

It also doesn’t mean it didn’t actually hear a difference - your unit could have had a fault, etc etc.

But on a forum like this the level of acceptable proof needs to be a repeatable experiment - measurements/blind tests being the most common.

 

[OldManMatt]

I’ll give the standard reply - unless you did a blind, level matched test then you can’t be certain you perceived anything audio-wise at all.

That doesn’t mean you aren’t sincere in your belief that it sounded different - it’s just that there are so many factors involved, including human cognitive biases, that without such tests, or some measurements, your perception doesn’t in itself hold much weight.

It also doesn’t mean it didn’t actually hear a difference - your unit could have had a fault, etc etc.

But on a forum like this the level of acceptable proof needs to be a repeatable experiment - measurements/blind tests being the most common.

I totally get it. And days of trying my best to level match compare are long gone. These days I have a process & it is what it is. But that's also why I love & appreciate all the work & effort that goes into this forum.

I just now came across this review & my diagnosis is that it's not bad. So of course it makes me question my personal experience. At the time my bias was hoping for something positive..positive was the general consensus in the Hifi media. But again, instead of walking away with perceiving no difference..& definitely not positive difference I came away thinking it was better left out of the system.

I guess what I should have asked was, Is there something in the data/measurements that I'm missing or not understanding that could account for my perceptions? I am completely ignorant when it comes to DDC's. Digital in general is not something I took to until the last 5 years maybe. I didn't even bring CD's into my home until the late 2000's. Dacs, CD players, transports were things I did not dwell on. I'm one of those people who held onto cassettes for too long.

 

[john61ct]

DDCs unless total junk, tend to be acoustically transparent, digital be digital.

Within S/PDIF - AES/EBU, TOSlink and Coax - are just flavours, physical format transfer more than any "conversion"

USB as the OUTPUT format tends to be rare, going through a PC or SBC for Host mode is often the way to go.

I love units like Schiit Eitr 2 and Topping D10S (or B, also a DAC) that are multi purpose, all outputs concurrently active.

I hate HDMI for audio, and IMO I2S is only for inside a case, board-level hacking.

For lotsa ports you can get crazy low prices on Firewire stuff, for good reason.

I love ADAT expansion, wish it were used for consumer multichannel.

Wiim Ultra + Topping D10S to help with DSP and bass management

Wiim Ultra makes not only a great preamp + streamer / network player, but has got basic DSP functionality. For overall system PEQ, using REW + other filter creation tools even an automated room compensation EQ "Autofit". Its bass management is for me too basic, as I need midbass couplers and...

www.audiosciencereview.com

ISO stereo S/PDIF Source Switchers, (or Analog?) many inputs

Assume something like Wiim Ultra as "digital hub", want to route all possible source devices through preamp to benefit from DSP features and configurable max volume/voltage for speaker protection. (Is that latter a rare feature on preamps?) Problem is the limited number of inputs, so...

www.audiosciencereview.com

ISO DDCs with USB Output, act in USB Host mode, work without a computer

I thought one of the HiFiMe devices worked like this, turns out I was mistaken got bad info. Not looking for an ADC or audio interface, or hybrid DAC / mixers etc, but if these do exist with this capability, please do post. Technically the Wiim devices' USB output do qualify, but those are in...

www.audiosciencereview.com

DACs or DDCs with simultaneous concurrent outputs

Looking to collect a list. No need to post all the details, just list the inputs and which outputs are concurrent. Compare / contrast features / SQ issues welcome if known to you.

www.audiosciencereview.com

 

[dark132]

I totally get it. And days of trying my best to level match compare are long gone. These days I have a process & it is what it is. But that's also why I love & appreciate all the work & effort that goes into this forum.

I just now came across this review & my diagnosis is that it's not bad. So of course it makes me question my personal experience. At the time my bias was hoping for something positive..positive was the general consensus in the Hifi media. But again, instead of walking away with perceiving no difference..& definitely not positive difference I came away thinking it was better left out of the system.

I guess what I should have asked was, Is there something in the data/measurements that I'm missing or not understanding that could account for my perceptions? I am completely ignorant when it comes to DDC's. Digital in general is not something I took to until the last 5 years maybe. I didn't even bring CD's into my home until the late 2000's. Dacs, CD players, transports were things I did not dwell on. I'm one of those people who held onto cassettes for too long.

The human ear is far less sensitive than testing equipment; however, while such equipment can verify technical accuracy, it cannot guarantee pleasing sound, as "pleasantness" is a matter of subjective emotion. SMSL’s value lies in ensuring a clean digital source, yet the human ear may not even perceive the higher levels of jitter present in other devices—which is precisely why Hi-Fi doesn't necessarily require heavy spending, whereas Hi-End does. In my view, Hi-End is ultimately about emotional value, as most people's ears struggle to distinguish the subtle improvements that separate Hi-Fi from Hi-End.

 

[dark132]

By the way, I’d like to remind everyone who buys the SMSL PO100 Pro to make sure to test whether the 24/192 signal works correctly. When I first bought one, only the 24/96 signal worked; the sound would cut out when upsampling to 24/192, regardless of whether I used a coaxial or optical connection. I had to return and exchange the unit before it would output 24/192 properly.

 

[OldManMatt]

The human ear is far less sensitive than testing equipment; however, while such equipment can verify technical accuracy, it cannot guarantee pleasing sound, as "pleasantness" is a matter of subjective emotion. SMSL’s value lies in ensuring a clean digital source, yet the human ear may not even perceive the higher levels of jitter present in other devices—which is precisely why Hi-Fi doesn't necessarily require heavy spending, whereas Hi-End does. In my view, Hi-End is ultimately about emotional value, as most people's ears struggle to distinguish the subtle improvements that separate Hi-Fi from Hi-End.

That makes sense to me

 

[tmtomh]

The human ear is far less sensitive than testing equipment; however, while such equipment can verify technical accuracy, it cannot guarantee pleasing sound, as "pleasantness" is a matter of subjective emotion. SMSL’s value lies in ensuring a clean digital source, yet the human ear may not even perceive the higher levels of jitter present in other devices—which is precisely why Hi-Fi doesn't necessarily require heavy spending, whereas Hi-End does. In my view, Hi-End is ultimately about emotional value, as most people's ears struggle to distinguish the subtle improvements that separate Hi-Fi from Hi-End.

You had me until the last clause of the final sentence.

 

[dark132]

You had me until the last clause of the final sentence.

My neighbor can't even tell the difference between $250 headphone and $2,500 one.

 

[tmtomh]

My neighbor can't even tell the difference between $250 headphone and $2,500 one.

I'm not sure what that says about your neighbor, given that I don't know the measured performance of either headphone.

 

[terryforsythe]

My neighbor can't even tell the difference between $250 headphone and $2,500 one.

I have a pair of IEM's, Truthear Gate, that I got on Amazon for $22.14, including tax. Paired with a JCALLY JM20MAX DAC ($16.57 on AliExpress), they sound fantastic. I am floored at the sound quality that amount of money gets us these days.

 

[dark132]

I have a pair of IEM's, Truthear Gate, that I got on Amazon for $22.14, including tax. Paired with a JCALLY JM20MAX DAC ($16.57 on AliExpress), they sound fantastic. I am floored at the sound quality that amount of money gets us these days.

Almost all in-ear headphones are excellent; I own the Chu II and Zero 2 and am very satisfied with both. Of course, full-sized headphones have the advantage when it comes to listening to classical music.

 

[dark132]

I'm not sure what that says about your neighbor, given that I don't know the measured performance of either headphone.

hd650 vs LCD3

 

[Paweł L]

I use the unit to convert USB to optical so I can make use of BB DAC in my older 'heavy duty' Demon AVR sitting 4m away. And this thing is so handy as USB input, with my cellphone using HiBy player or PC running Foobar2000. Also perfect ground loop insulator.

 

[OldTimer]

Mine is SMSL PO100AK. Don’t know if it performs the sama as your PO100PRO. I use it for iPad Pro 12.9 USB-C to Coaxial output for over 4 years. Satisfied.

 

[Paweł L]

hd650 vs LCD3

Seriously, blessings or a curse, depends how you look at it.

 

[john61ct]

Mine is SMSL PO100AK. Don’t know if it performs the sama as your PO100PRO.

as basic USB-to-SPDIF converters yes

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

S.M.S.L PO100, PO100 PRO & PO100 AK Measurements Hey folks, It is time for my very last review of the year. A very special one, as there are three products to be measured today ! S.M.S.L released earlier this year the PO100, a tiny and fairly cheap USB to S/PDIF interface. Later in 2022...

www.audiosciencereview.com

 

[OldTimer]

as basic USB-to-SPDIF converters yes

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

S.M.S.L PO100, PO100 PRO & PO100 AK Measurements Hey folks, It is time for my very last review of the year. A very special one, as there are three products to be measured today ! S.M.S.L released earlier this year the PO100, a tiny and fairly cheap USB to S/PDIF interface. Later in 2022...

www.audiosciencereview.com

The old integrated class A/B amplifier is not ready to die yet. There’s no USB audio input. Even I add a Class D amp to the rec-out to lengthen its life. Now the electricity usage has dropped a lot.