I've spent countless hours searching for a small, good quality passive speaker. In a roughly 4 inch cube size. That comes with an good (acoustically) box/enclosure. Plenty exist in various forms (kits) but I never know if they sound as good as even laptop or phone speakers. Which is a low bar, but still can't find good reviews.
A 4-inch cube doesn't leave much room for a passive speaker to be very good (depending on one's definition of "good").
We've got hard physical constraints with loudspeaker systems, and they show up as tradeoffs.
Very broadly speaking, in practical terms, this takes the form of a tradeoff betwixt enclosure volume, efficiency, and low-end frequency extension. It's impossible to improve all three of these at once. This was formalized with Thiele and Small's work ~60 years ago.
We get by with amazingly good small, self-amplified, active speakers these days because -- as a system -- they don't have the same constraints.
At their root, they're still just passive speakers... but whole of an active system comprises more than that. We can use EQ to improve low-end extension. We can use bigger amplifiers to make up for lack of efficiency.
We can use combinations of dynamic EQ and bigger amps to make small systems sound pretty darned good even at low volume and hold together nicely at higher volumes, thanks in part of some of the work of Fletcher and Munson nearly a century ago and also to modern measurement systems and the inexpensiveness of implementing functions (with DSP in 2026) that would have been unthinkably complex in the consumer analog space at any point on the timeline.
But while active speakers can be pretty neat, small passive speakers suck. They have always sucked in some way. They must always suck in some way compared to their larger peers, and a cube shape always makes some aspects of the suck even worse. Them's the breaks.
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Anyway, the market wants small, active speakers these days...so we get small, active speakers. Reviewers are people too, and they review what people want to buy.
If I may ask: What's driving your desire for a small speaker that is also passive?