My pet theory is that stupidly powerful rare-earth magnets, and class D amplifiers are the two main things that killed "hifi" type audio. No more black magic needed messing with transistors and op-amps on bespoke circuit boards that used to be the moat for these oldschool brands.

My Alexa Echo Dot 4 sounds better than my home audio setup from the 90s. Now, a fair comparison would be to a modern floor speaker with modern magnets and amps, but I'm too old for this :-)

> My Alexa Echo Dot 4 sounds better than my home audio setup from the 90s

I have a hard time believing this… yes today’s small devices sound better than small devices ever did. A lot of work went into that because people appreciate the reduced footprint. Also, those speakers are super cheap in comparison to the budget people would allocate to their stereo setups in the day.

But I’ve never heard a small speaker sound better than a 1970ies or later hifi amp + speakers from a decent brand. With big speakers you can reproduce all these frequencies without physics tricks. The sound is more laid back and the soundstage fills the room.

All the recent engineering has gone into making speakers small, cheap and wireless, like in the 90ies it went into creating multi-channel audio, but I would say stereo sound quality, as used for popular music, already peaked in the 70ies / 80ies.

Of course you can still get those quality hifi components today, or even better than that, but the median household is not listening on that and I’d wager has worse sound today than was the norm in the physical media era.

The opamp back in the days were pretty terrible. NE5532 was the king of audio opamp for decades until the early 2000s.

Modern Class D are built on advanced semiconductor processes (they are considered legacy node in the eye of Hacker News's primary audience. They are at least a lot better than the early days in terms of performance in analog domain.) When an IC company spend a lot of R&D money to develop Class D amp, they for sure exhausted what they can do before they tape out. That results in the superbe performance of modern Class D amplifier.

There is still oppertunities in getting analog Class AB type of amplifier working better, such as adding motional feedback control sensor-less or with sensor. KEF recently released a motional feedback soundbar with back-EMF voltage as sensor. It sure improve the sound quality for a soundbar. Although physics is physics, one cannot make a 1 inch speaker sounds like a subwoofer, but motional feedback sure can make 10 speakder sounds like a 15 inch subwoofer.

Sound reproduction is not just a flat frequency response. Perfect reproduction of phase information generates wider 3D sound stage, without the need of DSP to fake it.

Speaker box design advanced dramatically since the 90s too. The start of it was then - Bose made a lot of noise with compact-for-the-time stuff - but it's really advanced since then. Compare the sound quality of a laptop then with a larger MacBook now. And when you can get decent sound at decent volume out of a small package a lot of people don't want to give up a ton of space for extremely-good sound at high volume.

If your Alexa d4 sounds better than your home hifi the your home hifi wasnt.

It's advancements in delta-sigma DACs during around 2005-2015. So amps. Bit depths and noise levels improved massively. It's that that solved audio.

Digital music through digital systems has a lot of glorious qualities. But listening to records through my tube marantz or zenith amplifiers sounds way better to me. Tell you what, I’ll set up my Smaart rig (rational acoustics) in the room and see if I can find evidence :)

Good class Ds are not that cheap. Hypex and now Purifi based amps are good but not what I’d call cheap. Evenso lots of people like AB amps and some even like the old A amps fooling around with their “valves”.

> and class D amplifiers are the two main things that killed "hifi" type audio

class D amplifiers is to hifi, what lung cancer is to lung. /s