Why such a huge difference in SINAD measurements for the same model?

[bracko]

Hi all!

Measurements in different magazines can differ quite drastically, like in the case of Marants Model 40n (or Marantz HD-AMP 1).

MARANTZ Model 40n​

audio.com.pl

Marantz Model 40n integrated amplifier Measurements​

www.stereophile.com

According to AudioPL the SINAD for this amp is approximately 63 dB. According to Stereophile the SINAD is 86 dB. Quite an amazing difference (14 times higher noise level in one of the measurements). Similar difference can be seen for Marantz HD-AMP1 when comparing measurements on Audio PL and ASR. The SINAD difference is amazing 8 times.

https://audio.com.pl/testy/stereo/wzmacniacze-stereo/2607-marantz-hd-amp1#laboratory

Marantz HD-AMP1 DAC and Integrated Amplifier

This is a review and detailed measurements of the all-in-one Marantz HD-AMP1 DAC and integrated amplifier. It is on kind loan from a member and retails for USD $1,100 including free Prime shipping from Amazon. The unit has a somewhat retro looking of other Marantz audio products with the round...

www.audiosciencereview.com

Can this be attributed to different specimens tested?
Which one of the measurements can be trusted? Can any of them be trusted? Are the measurements on AudioPL consistently lower than those on Stereophile?

Grateful for your comments!

 

[danadam]

There already is a topic about that (I think):

Why is EVERY amp on this polish website at low signal output 20 dB worse than @amirm´s measurements

A Guy from Poland who is running a yearly HiFi show in Warschau does pretty much the same thing as Amir does: Measuring amps (some hundreds of them!) What puzzles me, is that all his measurements with small signal (look at 100 milliwatt) are showing about 20 dB worse results as @amirm!!! E.g...

www.audiosciencereview.com