Audio Science Review of Expert 200.

[Confused]

Maybe these measurements are also helpful https://www.stereo.de/hifi-test/produkt/...0-pro-1585

Thanks for posting @markush.  

I am finding myself fascinated by measurements at the moment.  I know some people might think this is a little sad, but at least it something interesting to study during "lockdown".

I actually recall seeing the above measurments on another thread, where a few of us at the time were obsessing about power outputs.  The stereo.de review was notable as one of the first to measure the 220 Pro, and it was particularly notable that it achieved 170w / 8 ohms, 343w / 4 ohms, which is arguably superior to the D-Premier, which managed 180w / 8 ohms 245.8w / 4 ohms, and certainly a big step up from the 120w / 8 ohms, 240w 4 ohms HFN measurements for the D170.  How much this matters is debatable, but it does hint at how the amp and power supply design has improved over time.

For those that might be interested, I notice that Stereo have also published measurements for the 210 Pro dual mono

https://www.stereo.de/hifi-test/produkt/...-dual-1807

There are a few things I noted in the Stereo measurements:

They only measured via the analogue inputs for the 220Pro, which as we have seen elsewhere do not measure quite as well as the digital inputs.

The 220 Pro measurements show S / N ratio Phono MC (0.5 mV / 10 ohms) at 5 watts: 74 dB (A).  This appears to be a worse result than anyone one of us achieved in the thread linked below:

https://devialetchat.com/Thread-Phono-st...asurements

This makes me wonder if there is some variation in the performance of the phono stage between units?  Or maybe just a quirk of how the measurements are reported?  I note that those who seemed most concerned about hiss never actually made a recording to send to Mathieu Pernot.  Maybe we are missing some interesting data here, that is the worst performing phono stages might not have not been measured yet?  Just idle speculation on my part.  (although I recall @Greg was waiting for a friend to perform the recording, and having a friend visit would not currently be legal or advisable during the UK's "lockdown")

The 210 Pro measurements do include a signal to noise ratio measurement via the digital input, 115dB, somewhat better than the analogue input measurements.

The 50 m/w signal to noise ratio for the 220 at 76db is fractionally superior to the 210 at 74dB (nothing in it really), but at 5w the 220 is even further ahead at 95dB versus the 210's 84.  I find this point interesting as it implies that the 220Pro is the superior amplifier, but I suspect the 210 may be the better sounding amp for other reasons.

Whist posting nonsense about measurements, I can advise that I have been having much fun this morning both listening to music and looking at the various amplifier measurements available on Paul Millers AVtech site.  I was thinking about the Devialet's quoted 130dB S/N ratio figure and the fact that Paul Miller measured 118dB for the D170, and I was wondering how rival products measure in this regard.  The interesting thing is that I could not find anything with a lower figure than 118dB, and nothing remotely close to 130dB.  As I mentioned in an earlier posts, you can match Devialet's measurements if you are very selective about parameters.  For example, Miller quotes a S/N ratio of -133.9dBV @ 40Hz, but quoting a S/N ratio of 130dB but only below 45Hz seems a bit tenuous.  The point is, the Miller measured S/N ratio at 118dB is excellent, and there are very many highly regarded products measured by Miller that are much worse in this regard.  So why quote figures like 130dB?  This does open Devialet to acusations of quoting meaninless numbers which cannot be backed up by measurements, which seems a bit daft to me when the actual figures backed up by recognised peramiters are themselves excellent by any satandards. 

The AVtech measuremnts are only available for reviews 2013 and earlier, so do not include the current ASR favoourite of the Benchmark AHB2, but the HiFi News review is available online, and reports a measured S/N ratio of at 0dBW / 100W = 106.0dB / 126.0dB.  So yes, the AHB2 does have better numbers, for noise at least, and is just about the only thing that I have seen that gets anywhwere near the S/N ratio numbers quoted by Devialet.  In fact, mindfull of all the other measuments of decent kit I have looked at this morning, the Benchmark numbers are pretty remarkable.  I wonder what it sounds like?

https://www.scvdistribution.co.uk/files/...nt_1_3.pdf

https://www.stereophile.com/content/benc...-amplifier