Now here is a newb question, aren’t they all “budget” brand amps now a days built across about 3-4 different factories lol?
I'd say that S&I and Zenon can still make some pretty abuse resistant amps, but the thing is in dealing with those far east buildhouses is that they'll give you what you order/pay for. If you ask for a 4500W amp that'll have a good chance of surviving .5 ohm they can probably deliver, if you ask for a 4500W amp that you can buy for 300$ a pop they'll cut corners until they can make you something that more or less fits the bill.
Even American shops are like this to some extent. Nobody really ran around saying that AC Delco made an amazing head unit, but when Rockford had their first run of head units in the mid 90s they were made by Delco (to RF specs) and were some of the highest quality source units on the market at the time. Hell, even China can manufacture good electronics and do so for all of the top name brands, the catch is someone like Alpine or Kicker isn't going there to try to cut cost to rock bottom and has the ability to enforce their required level of quality control and will do their own R&D in house.
The point being, the difference between a 600$ MSRP 5K amp and a 1200$ MSRP 5K amp isn't just because some companies are greedy and others are selling amps at a loss and we should expect the cost cuts to reveal themselves over time or under stress.
Anyway, for what it's worth I'd consider the quality of electronics you can source from Korea these days to be about the modern equivalent of buying electronics from Japan in the 80/90s, they've been at it a long time now and while they still don't have any great innovators, they are doing low cost and build quality as good as we could do domestic. And generally speaking companies who just slap their name brand on something out of a catalog (basically everybody selling a 5k+ amp) aren't trying to get high quality from China, they're shopping there for low cost first and foremost.
All that aside, .5 ohm is absolutely torturous on semiconductors any way you slice it and you really should be planning on enjoying hit or miss ability to keep things out of protect and premature and potentially catastrophic failure if you want to play the half ohm game.
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