I'm pretty sure everything small and portable uses switching amplifiers, in fact pretty much all modern consumer electronics use class-D from your phone to your TV unless you specifically seek out separates from an audio shop. This is because class-D amps are extremely convenient, they are small, cheap, power efficient and they require little consideration for cooling - audio quality is an area of debate, there are certainly lots of very poor quality class-D amps our there with absurdly high THDs, but there are probably lots of good ones too.

AB would be more likely than A, but I can't imagine finding them even in a large flat screen TV since they are inherently less efficient and require larger power transformers which make them fairly heavy and bulky. You only really find non switching amps these days when people want to sacrifice some of that convenience for some nicer sound.

The trifecta of outstanding power efficiency, low cost, and nowadays very good performance of a class D amp virtually guaranties that any amplified sound you've head from a mobile device, or any consumer device really, was amplified by a class D.

There's not really a good reason to use non-class D in any mobile application today. As few as 10 years ago I thought Class D = garbage you settle for if you must, I've heard some incredibly good Ds that have made me completely change my mind

Just to throw an extra confounding factor in, I can guarantee that your hearing now isn't as good as when you first heard them. But that's fine, it's the subjective experience that counts.

Sound is weird and I agree it is a subjective experience.

I’ve done some unscientific blind tests with nice modern class Ds on people who avowedly think all digital amplification is trash. 9 times out of 10 the reaction has been something like “hmm, how lovely, now when are you going to show me the digital amp?” After I tell them what it is, it becomes “oh yeah, I can hear it now. It’s fine I guess for casual listeners but clearly lacks X.”

People consistently report higher levels of satisfaction with more expensive wine versus cheaper one, even if it’s just the same wine rebottled. They’re not lying, our perceptions and preconceived notions genuinely affect the we experience reality.

I tried many Class-Ds - and all of them caused fatigue. The initially sound even better than AB, but in 15 minutes I get tired.

Fatigue is an interesting factor as there is no physiological bias involved AFAICT - when you can't listen any more you just know, it's almost physical.

I have noticed different headphones and using a class AB headphone amp vs builtin switching amps can significantly impact how long I can listen for... But that anecdotal correlation is not enough for me to assign blame to switching amps, it might just be crap switching amps... or switching amps with not enough headroom. The problem is class D is always used for cheap low power devices, so most bad experiences are inevitably going to strongly correlate with class-D - whether or not it's attributed to the fundamental property of switching vs just being a bit ... shit.

Blinded or unblinded?

Both. I do not believe that non-blind tests are worthless. When you are dealing with subtle effects, knowing what to listen for actually helps in detecting the difference. However, I tried both blind and non-blind. Did not like both times. I really wanted to like Class-D though, it is not like I was prejudiced.

When my amp/receiver bought the farm a decade ago, I decided to try a 50-watt/channel 12-volt class-D amp after seeing the specs. It cost under $50, and I powered it with a hefty wall-wart (120v-1.5amp to 12v) left over from the 90s. It's been on 24/7 since, never used for over 10 watts/ch. The savings went into a decent pair of near-field speakers ... the most important part of great sound.