Yeah and the fact that despite fairly mediocre measurements, I was able to procure my 2 receivers at a fraction of their original cost, perhaps made me far more likely to take a chance.
To my astonishment, even on the lowest level model, it sounded for all intents, quite good!
Frequency response, and so on, and amplifier power and all that matter a lot more I guess.
But just sitting here listening, NOTHING seemed sub-standard in any way.
SINAD for sure has a place in measurements, but with my experience of these 2 AVRs, not sure it defines what is good and not good, but maybe more of a tie breaker if all else is equal?
If you calculate SINAD for highly regarded Audiophile amps of the 80's - eg: Quad 606, SN=105db, THD= 0.01% - SINAD calculates as: 80
By the measures of the SINAD gazers, this highly regarded, highly reputed amplifier, is a poor performer!
Or lets look at the legendary Nakamichi Stasis PA5 amp - THD at rated power = 0.1% SN=120db... so noise is not an issue! - but the THD amounts to SINAD = 60 - so on the SINAD gazer chart - this is in the Junk category!!!
Or how about a legendary Krell FPB200 - it has THD ratings at 1kHz and 20KHz, and does worse at 20kHz - lets be positive and use the better rating... THD= 0.02% or SINAD = 74
Yes we now have amps that can do better - much better - the direct descendant of the Nakamichi Stasis feed forward design, and the Quad Current dumping design (very close relatives!) - is the highly regarded Benchmark AHB2.... its THD is specified as 0.0003 or SINAD = 110 (!!!!)
Amir measured it at an astounding 113db
(Keep in mind all the specifications are at "Rated Power" - whereas Amir is measuring at 5W.... typically amps have lower THD at rated power than at lower power outputs.... so achieving 3db better than spec at 5W is quite a spectacular result!!)
Having said that - we can look at a whole collection of amps, which are universally regarded as top performers from the last 40 years... and we find that the SINAD "Bar" for these amps is (drumroll) ... 60
If the Legendary Nak Stasis could wow the cognoscenti with a SINAD of only 60 - why are we fussing about it !?
Well... a high SINAD is a sign of very good circuit hygiene, it is an indicator that great care was taken not only in the design but in the manufacturing and adjustment... If your shortlist has 2 amps one with a Sinad of 70 and the other with a Sinad of 90 - picking the one with the higher Sinad would make perfect sense.
Looking at current AVR's, a THD of 0.08% = SINAD 62 (Onkyo RZ50, Denon X3700H) - so their amps do better (in SINAD terms) than the classic Nak Stasis!
But there are lots of other things to check out in performance terms...
So yes - a tie breaker, and nothing more.... I would look askance at anything with a SINAD below 60 for sure.... but anything over 70 in the power amp area seems fine, and for the pre-outs I have higher expectations! I expect something in the 90's.