Looks like his gear will be for the Chinese 220 volt single phase. So 240 volt in the USA is different.
The LittleDot isn't going to use much power.
Many of these stepup transformers claim 5000 watts or 3000 watts, but stepping up 120 v USA you'll be limited to 1800 watt input. So they aren't being honest or safe. Possibly they work at the higher ratings as a step down, but are limited in the other direction as a step up.
https://www.amazon.com/SEYAS-Transf...p+up+transformer+220v+to+110v#customerReviews
This unit is rating for 1000 watts and has better reviews. Certainly more than enough for your LittleDot. As for your power amp I would think this would suffice until somewhere around 150 wpc on the amp output assuming two channels.
Someone may have suggested 3000 watts taking into account what you actually get which might be only 1000 watts from the one you linked. You'll notice most complaints were with people using devices above 1500 watts which in one direction (step up) the unit could never safely provide with an 18 gauge power cord. So even the unit you linked to might be okay if you don't use it for anything close to its rated output.