Amplifier's rising measured distortion (SMSL vs Yamaha), should I be concerned?

[whazzup]

Had the SA300 for some time, and just thought I'll do some quick measurements between it and the Yamaha A-S500. Found an interesting difference.

Before that difference, you can see the measured frequency responses for both amps below (Download REW measurements here).
I've kept the Xonar U7 dac / Windows volume constant and varied the volume so that both amps register 96 dB on 1 kHz tone on REW. However, SA300's increments are more coarse, so I settled for ~0.5 dB higher volume than the A-S500. Mic is about an inch from the cone center.

Blue (Yamaha) / Orange (SMSL) charts - JBL A130 tweeter and mid
Green (Yamaha) / Orange (SMSL) charts - JVC UX2000 (as a representative for 4 ohm rated speakers)

In the context of these 2 speakers, the SMSL is performing as well as the Yamaha, both FR tracking each other end to end.


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The difference that I spotted was in the distortion graphs. When measuring the A130 tweeter, SA300's distortion went up about 5 dB beyond 15kHz.

Distortion for Yamaha. No rise beyond 15 kHz. *Correction: ~2-3dB rise.

Distortion for SMSL. >5dB rise beyond 15 kHz.

Final FR didn't seem to get affected though. Not sure the significance for this. Should I be concerned? Is it not good for the attached speakers, since the speakers has to play the distorted signal?

 

[Vini darko]

Cheap class D itermodulation distortion is the likely culprit in the smsl. Possibly maybe also ultrasonic noise causing issues. Yamaha have been making those class ab amplifiers for 40 years so you'd hope they have it dialed in by now . Shouldn't be dangerous to your speakers maybe unpleasant for the ear prehaps.
Most of the low cost switching amps measured here have rapidly rising high frequency distotion.
Note: not claiming class d bad ab good. Both can be good or bad.

 

[whazzup]

Cheap class D itermodulation distortion is the likely culprit in the smsl. Possibly maybe also ultrasonic noise causing issues. Yamaha have been making those class ab amplifiers for 40 years so you'd hope they have it dialed in by now . Shouldn't be dangerous to your speakers maybe unpleasant for the ear prehaps.
Most of the low cost switching amps measured here have rapidly rising high frequency distotion.
Note: not claiming class d bad ab good. Both can be good or bad.

Thanks! That's comforting to know. The rising distortion didn't seem to impact the measured FR, and I don't think my ears picked up anything.
Still, it's interesting to learn about these differences.