Early on people were saying the same about the Egret 2 mini but the power cable issue was proven correct in the end. This, the original astro mini and the egret mini were all built by the same company.
DISCLAIMER: I'm not an electronics expert by any means, I'm just putting together some obvious things I saw when researching this. More than happy to step aside if someone with a better knowledge base wants to correct me, or fill in the gaps.
The issue with the Egret is (allegedly) with the available current on the power supply.
In the Egret mini II thread, there was a tweet from a Japanese user
who did some informal testing using various Apple and Anker USB adapters with different max current limits. The video shows that, when specifically playing Rayforce, there seems to be a decrease in lag as you increase the max current limit on the power supply, with best results using an adapter with a 3A limit.
Now, I don't think anyone's done a proper lag test on all the games on the Egret mini, with different power supplies. (If they have, I haven't seen it.) My subjective impression from running the Egret on an Apple 5V/3A adapter is that there's still enough lag to be bothersome on certain titles, particularly with twitchy games like Arkanoid, but YMMV. It's also unclear whether there's a difference in lag over HDMI vs. playing on the tiny LCD.
Everyone's working assumption/hope is that, since the same manufacturer is apparently responsible for the Astro and Egret minis, that this weird hack of mitigating lag with a higher current power supply might carry over to the Mini V. I don't know what this is based on. The systems share an SoC, but the boards are clearly different. (
This picture shows the board layout of the first Astro City mini, while
this Tweet from Slinky Ramune has board shots for the Egret mini.) Hell, you can just look at the back of the units, notice that the ports are laid out differently and the USB power connectors are different, and come to the same conclusion.
(It's also worth noting that, on the software side,
Taito had apparently released a Linux kernel archive for the Egret which ended up just being the older Astro City source, and was apparently missing the LCD panel driver for the Egret. So that's a point in favor of the systems being similar, but with significant differences.)
It's obviously still worth
testing whether higher current power supplies might help with lag, as buying and swapping USB supplies is trivial. However, you might want to temper your expectations. Retro Core posted a
video where he ran a Mini V on what he says is a 2.4A Anker USB charger, and played on the mini LCD instead of using the HDMI output. People in the comments claim there seems to be 8-10 frames of lag at various points, which I guess they estimated by pausing and single stepping through the footage. That seems to be consistent with the worse results in
these informal tests. (In particular, one user calls out an 8 frame delay @ 4:09 in Batsugun, which matches what MOF reported on his list.) That's ... not good, and suggests that the next tests should try 3A for comparison (which is the USB 2.0 Power Delivery limit).
Additionally: some titles in the Mini V collection apparently have
input lag on original hardware, which means any further testing would need to take this into account.
(Side note: USB 2.0 Power Delivery has a hard limit of 3A in spec. The
USB 3.2 Power Delivery spec, in sec. 10.2.2, states that "currents higher than 3A are allowed to be offered up to a limit of 5A, given that a 5A cable is detected by the Source, and the Voltage times current remains within the Source PDP Rating." Translation: you're not supposed to be able to pull > 3A @ 5V over USB without a special, chip-containing, 5A rated cable which is identified by the USB controller. It's highly doubtful that
any of these mini consoles would support that (esp. since they're rated @ 2A), so let's say that 3A is the theoretical upper limit for now (assuming these systems actually care about spec.) It's your money, use your own judgment.)
I still think it's a bad idea to use the Raspberry Pi's 5.1V adapters. In the case of the Mini-V, if you use the official
micro USB Raspberry Pi supply, you can't even draw 3A -- it maxes out at 2.5A.
As for the Turbografx Mini ... it seems like there's 2 different USB related issues. One is the rumor around the Raspberry Pi power supply bricking the console, which was mentioned in (and maybe originated with???)
this Amazon review. The product he links to is some random no-name 3rd-party Pi case and power supply, and the picture clearly indicates that it's 5.1V/3A, not 5V/3A like he claims. The non-standard voltage isn't great, but I think it's also just as likely that it was a defective power supply.
The other, more common complaint is that people got their units, were able to power them up, but then the controller wouldn't work and they couldn't get past the very first menu. It's still unclear exactly what the cause was, but after watching
this repair video, it definitely looks like
something's gone horribly wrong on the manufacturing side (defective USB chips? bad solder jobs? Both??).
The common thread through all these mini console reports is that manufacturers are refusing to ship proper power adapters, which puts users in the risky spot of trying to find one that doesn't suck and won't break their system. It's obvious they're doing this to cut costs, but I also wonder if they're trying to dodge responsibility when users run across a bad USB supply (because
they didn't ship said adapter). It's just one more sign that you aren't really getting what you paid for; rather, you're getting a product built to a specific price point, with all the compromises that implies.
On the up side, today I learned that USB power meters exist, and could maybe be a useful tool for troubleshooting power adapters and cables (
if the readings are actually accurate.) I ordered a random one off Amazon out of curiosity; we'll see how that goes.