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SPL Phonitor X Review (DAC & Headphone Amp)

ShiZo

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Looking at the nicely made cases and the guts of these things, it's easy to see why they are so expensive:

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God damn that's beautiful. Violectric has always been regarded as one of the best ss amp makers in the game. I'd definitely want to see this thing measured. I haven't had an amp yet make me upset about my hpa4 purchase (thanks benchmark), maybe the a90 based on saving money, but I got the hpa4 years ago.
 

peniku8

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It would be interesting to see a review of the Benchmark amp treated as headphone amp. I wonder how it would fare, although it's ofc massively handicapped by offering way too much headroom for low impedance headphones (high noise floor, relative to typical headphone amps) but it should do decently well with highZ headphones, which pushes down the audible noisefloor.
Would surely be an interesting video to see how the leading speaker amp performs as headphone amp :)
 

Jimbob54

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It would be interesting to see a review of the Benchmark amp treated as headphone amp. I wonder how it would fare, although it's ofc massively handicapped by offering way too much headroom for low impedance headphones (high noise floor, relative to typical headphone amps) but it should do decently well with highZ headphones, which pushes down the audible noisefloor.
Would surely be an interesting video to see how the leading speaker amp performs as headphone amp :)

My money is on it not performing as well as the leading sub $200 headphone amps.
 

Sascha [SPL]

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We are usually happy about every review, since we are pretty sure that our devices get top marks – which is generally the case. However, this review surprised us a bit, and above all, it confused us.

Personally, I would expect any serious reviewer to consult the manufacturer before publishing a review if the test result is not what was expected and leads to questions. Perhaps this is no longer to be expected in the fast-moving times of Internet forum culture – but it makes me wonder. A short research or an inquiry of the manufacturer would certainly have brought some light into the darkness.

Let‘s first start with the test device itself. This Phonitor x is an older device, which differs from current devices in terms of features and design.
1-Amir-Phonitor-Titel1.jpg

All SPL devices of the Professional Fidelity series, which also includes the Phonitor x, have white labeling on the front for some years now. The first devices had a gray labeling – but because of better readability, we relatively soon decided to use the color white. The gray was initially chosen for a more modest look.

2-Amir-Phonitor-Rear-Titel1.jpg


On the photo of the rear side, we as the manufacturer also directly see that the device has a very old version of the DAC192 installed, which was already removed from our product portfolio some time ago and replaced by the DAC768xs with AKM 4490 chip.

3-Amir-Phonitor-Zitat-1.jpg


In fact, we know this misbehavior from DAC192 modules with the first software generation installed. However, this only occurs in connection with certain software, such as the Audio Precision software used in the test. If Audio Precision software is active on the computer, it blocks the ASIO driver for the DAC192. Of course, this problem has also been fixed in the meantime.

We don‘t need to comment on the paragraph “SPL Phonitor X DAC Measurements” in the review that deals with the DAC in this context, since this is not a current production model. Unfortunately, the complete first part of the review is misleading, since it was not the DAC768xs which was measured.

We would like to point out that the DAC192 and DAC768xs generally have an output level of +8dBu at 0dBFS, which corresponds to 2V. The SPL DAC768 has an output level of +15dBu at 0dBFS. Possibly something got mixed up there. Why 4V are expected in the review for this DAC is otherwise not clear to us in this context. The measurement confirms the 2V.


We have repeated the measurements made in the review, but this time with a series device with built-in DAC768xs and would like to share the measurement protocols here.

4-Meters1.jpg

We see an approx. 20dB better SINAD value in our measurements and also in the THD+N measurement we are better by one decimal point. Of course, the RMS level is also about 2 volts here, as it is to be expected for the DAC768xs.


5-SINAD1.jpg

When measuring the SINAD vs. Messured Level, we see that our measurement from the DAC78xs leads to much better values. Our measured values are between 92dB and 102dB – in contrast to the 82dB stated in the review – and are thus at least 10dB better.


6-FFT1.jpg

The measurement of the jitter noise is also in a completely different class. Thus, the noise here is always far below 140dB.


If we look at the next topic of the review “SPL Phonitor X Pre-amplifier Measurements”, we also have to correct some statements.

7-Amir-Phonitor-Zitat-PreAmp1.jpg

The display range of the VU meter can be adjusted via DIP 3 (see label on the back of the Phonitor x – e.g. on the photo of the back of the device). If the DIP 3 was in the “On” position, the sensitivity of the VU meter would be reduced by 10dB and the needle would no longer be at the max. This is due to an incorrect setting on the device. The other DIP switches are used to adjust output levels and to activate other functions.

8-Amir-Phonitor-Rear-2.jpg


Here we also suspect other incorrect settings that can deliver incorrect measurement results as a result. We will deal with this later.

As mentioned at the beginning, “XLR input and XLR output in the back” were used for the measurement.
So the signal passes all stages of the device – the measured values are not “state-of-the-art” in the analog world?

At this point I would like to make a short statement about our development philosophy, maybe this will help to get a better understanding:
We have been developing analog audio equipment for almost 40 years. One of our most important principles is that a device must sound good. This is our maxim for all product developments. Almost our entire team consists of sound engineers and audiophile music lovers. We have noticed over all these years that devices with exactly the same measurements but different parts/components sound different. We always decide to use the best sounding components – no matter if they are SMD or have to be assembled with the most modern THT machines or manually on the boards. We always make this decision dependent on our sonically favored components. This decision is made individually for each board.

At the mid 90s, the desire to raise analog technology to a new sonic level grew in our team – the result was the development of the SPL 120V Technology. Even though this basic technology raised the measurements to a new level in the analog world, a purely digital signal path naturally has a better channel separation and signal to noise ratio. Somewhere, however, this signal must also return to the analog world and of course cannot maintain these values there.

9-Amir-Cross1.jpg

Here an analog potentiometer is compared to a digitally controlled relay cascade.
We don‘t want to go deep on the sonic advantages of an analog high-end potentiometer – but we are talking about a technical fact of a certain type of component. In our listening tests a high quality potentiometer for volume control always performed better sonically than other solutions. Maximizing crosstalk is not necessarily leading to a better playback sensation. If the channels hardly crosstalk the sweet spot becomes needle sharp. Vinyl for example has a crosstalk of just 15dB to 40dB. The pot we use in the Phonitor x has a crosstalk better than 85dB at 1kHz. We try to combine the best of the analog world with the digital one – our hearing does not work like a digital device.

10-Amir-10dB1.jpg

The balanced output stage produces an amplification of approx. +6dB. Of course, these 6dB are lost in the signal to noise Ratio measurement. In addition, the balanced headphone output has no shielding, which also reduces the value slightly. This deviation does not occur with the unbalanced TRS output.

We also provide – as already mentioned by a user in a comment (thank you :) ) – a video with a measurement with an Audio Precision and an Phonitor xe on our website. In the comments we read that the author refers to our Audio Precision Cascade 2 and makes a little fun of the device.
11-Amir-Phonitor-Zitat-AP.jpg


In fact, many newer Audio Precision devices have lower analog performance – only recently a new device has been released that surpasses the performance of the Cascade II. So, unfortunately, in some cases we are left with the good old Cascade II. Things are not always better just because they are new ;-)

12-Amir-Phonitor-Zitat-3.jpg

The “SPL Phonitor X Listening Tests” leaves us speechless. The Phonitor x has more output level than the headphones can handle – that‘s why the headphones overdrive. What is the message of this “test”? Or is there something we don‘t understand? We assume that the output level at the headphone output was increased by up to +30dBu via DIP1 and/or DIP2. This would also explain some discrepancies in the previous measurements and listening tests – especially when using low impedance headphones.

13-Amir-Phonitor-Zitat-4.jpg

We can‘t agree with this conclusion at all – many of our customers (and so do we as well) love the Phonitor headphone amplifiers in combination with low impedance headphones. This combination is praised by many renowned mastering engineers as particularly great and is their reference set-up. We get the same feedback from the HiFi world.

Mastering legends like Bob Ludwig trust in our 120V Technology – which besides the in the analog world outstanding great measurement values also sonically convince. A calm and relaxed sound that reveals the smallest details. A precise, realistic stereo image and very low hearing fatigue are values that audiophile music lovers and professional studio users appreciate in many cases.

With this sentence we would like to end this statement now and leave this thread here.

If you have any further questions about our products, please contact us via our website: https://spl.audio

With kind regards,

Sascha (On behalf of SPL)
 

Veri

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Good to see SPL chime in.

We see an approx. 20dB better SINAD value in our measurements and also in the THD+N measurement we are better by one decimal point. Of course, the RMS level is also about 2 volts here, as it is to be expected for the DAC768xs.
When measuring the SINAD vs. Measured Level, we see that our measurement from the DAC78xs leads to much better values. Our measured values are between 92dB and 102dB – in contrast to the 82dB stated in the review – and are thus at least 10dB better.
100dB just barely clears 16-bit requirement of 96dB. That makes the DAC768xs(thanks for measuring it) a far cry from DAC state of the art.

We would like to point out that the DAC192 and DAC768xs generally have an output level of +8dBu at 0dBFS, which corresponds to 2V. The SPL DAC768 has an output level of +15dBu at 0dBFS. Possibly something got mixed up there. Why 4V are expected in the review for this DAC is otherwise not clear to us in this context. The measurement confirms the 2V.
Amir measured the XLR line output of your DAC192. 2 volts over XLR outputs is not standard but quite low, +15dBu would be the more common output level over balanced XLR connection.

We can‘t agree with this conclusion at all – many of our customers (and so do we as well) love the Phonitor headphone amplifiers in combination with low impedance headphones. This combination is praised by many renowned mastering engineers as particularly great and is their reference set-up. We get the same feedback from the HiFi world.

Mastering legends like Bob Ludwig trust in our 120V Technology – which besides the in the analog world outstanding great measurement values also sonically convince. A calm and relaxed sound that reveals the smallest details. A precise, realistic stereo image and very low hearing fatigue are values that audiophile music lovers and professional studio users appreciate in many cases.
Good that it is subjectively fine, but it is quite obvious this design is optimal with high impedance headphones. It's kind of weird to "disagree" with measurements because people (mastering engineers or not) think it sounds great. That does not disprove the outlined weaknesses of your discrete design which are measureable and provable:

index.php

300/600 Ω loads correspond to good performance and incredible power output. The other loads don't correspond to very good performance.
 
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Jimbob54

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Perhaps you could ask SPl to send a current unit for evaluation?
Keith
Would be worthwhile and fair. I think the owner of this refurb unit tested has already initiated a return to seller and it would be nice to see an up to date model tested for the benefit of potential customers and in the interests of balance. As to whether the DUT under test here is representative of all models of the same age, we may never know.
 

Helicopter

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@Sascha [SPL] If you send a unit in for testing, then Amir will give you an opportunity to discuss what he finds before publishing the review. If a member sends it, then he doesn't. His time is too valuable.

Thanks for coming and welcome to ASR. It is always great to see participation like this.

Most of us don't really care about your expertise in subjective listening tests. If you do controlled and blind listening tests and share the parameters and methodology with the results, it will carry some weight. This is especially so for a product like this, which has a high price tag, brand heritage and mouth-watering industrial design. Of course people are going to be biased toward it in listening tests, regardless of experience.
 

GoldenOne

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It would be interesting to see a review of the Benchmark amp treated as headphone amp. I wonder how it would fare, although it's ofc massively handicapped by offering way too much headroom for low impedance headphones (high noise floor, relative to typical headphone amps) but it should do decently well with highZ headphones, which pushes down the audible noisefloor.
Would surely be an interesting video to see how the leading speaker amp performs as headphone amp :)
It works absolutely fine even with sensitive headphones. I actually use it as my main headphone amp.

Someone I know even runs iems on it now and then :D
 

branco108

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Would be worthwhile and fair. I think the owner of this refurb unit tested has already initiated a return to seller and it would be nice to see an up to date model tested for the benefit of potential customers and in the interests of balance. As to whether the DUT under test here is representative of all models of the same age, we may never know.
Yes, true please i really like SPL XE AMP but im not feel good if it is not in recomended amps from Amir. But i hear only good things about spl so i was little bit shocked when i see the results yes maybe it is trully some old unit.
 

Martin

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Nice to see @Sascha [SPL] respond. I was expecting it after corresponding with them through a support ticket.

Good to see the improved performance of the DAC768xs module I was told this unit had over the DAC192 module it actually did have.

I think SPL's design decision is an interesting one:
Here an analog potentiometer is compared to a digitally controlled relay cascade.
We don‘t want to go deep on the sonic advantages of an analog high-end potentiometer – but we are talking about a technical fact of a certain type of component. In our listening tests a high quality potentiometer for volume control always performed better sonically than other solutions. Maximizing crosstalk is not necessarily leading to a better playback sensation. If the channels hardly crosstalk the sweet spot becomes needle sharp. Vinyl for example has a crosstalk of just 15dB to 40dB. The pot we use in the Phonitor x has a crosstalk better than 85dB at 1kHz. We try to combine the best of the analog world with the digital one – our hearing does not work like a digital device.

Sascha states they chose an analog potentiometer for its sound, and more specifically because it introduces crosstalk. They then add in all kinds of fancy circuitry - which I understand works very well - to allow you to tailor crosstalk to your liking:
fancy circuitry.JPG


It seems an odd engineering choice. Would you not want to "maximize crosstalk" (I think Sacha meant minimize) so you feed the cleanest signal with the least amount of crosstalk into their fancy circuitry? Just my observation.

In any case it's good to see SPL standing behind their customer. They have instructed me "to return the unit." SPL will "have a meeting about this <particular> device on Tuesday." Fantastic customer support!

Thanks,
Martin
 

acbarn

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Nice to see @Sascha [SPL] respond. I was expecting it after corresponding with them through a support ticket.

Good to see the improved performance of the DAC768xs module I was told this unit had over the DAC192 module it actually did have.

I think SPL's design decision is an interesting one:


Sascha states they chose an analog potentiometer for its sound, and more specifically because it introduces crosstalk. They then add in all kinds of fancy circuitry - which I understand works very well - to allow you to tailor crosstalk to your liking:
View attachment 117841

It seems an odd engineering choice. Would you not want to "maximize crosstalk" (I think Sacha meant minimize) so you feed the cleanest signal with the least amount of crosstalk into their fancy circuitry? Just my observation.

In any case it's good to see SPL standing behind their customer. They have instructed me "to return the unit." SPL will "have a meeting about this <particular> device on Tuesday." Fantastic customer support!

Thanks,
Martin
Hopefully they back up their words with action by sending Amir a new device to test.
 

Veri

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