Sony WF c500 have what hifi 5 stars £59 has good review
The Sony c500 have a Sub Band Coding (SBC) latency of 240 milli-seconds (ms) Whilst your unlikely to notice when listening to audio, it’s highly probable you would notice when watching video/TV you will notice a lip sync issue. The Sony c500 are near SBC latency’s operating range of 260ms from memory. IOS latency is however 142ms but, you can’t compare watching video an an Ipad with a TV. Its not just SBC latency that matters Mike.
There are other wireless codecs such as aptX, apt X HD offers 24bit wireless tech and would be the closest you will get to “wired”. aptX low latency that eliminates slip sync issues. Many other wireless devices also incorporate this to fine tune-for example my LG.
aptX has a far lower latency than SBC and operates between 60-80 aptX low latency is just 30-40ms virtually eliminating sync issues. On the other hand SBC (can’t remember the exact range) is somewhere between 160-260ms.
You have got to take into consideration that most “in ear” buds are aimed at the dog walker, runner gym goer or those on the move, so can listen to audio not video. Youtube – watching a video on IOS or Android device is different.
The question is will the Sony c500 they be suffiecent to use without having any sync issues with a latency of around 240ms I wouldn’t like to say. Over ear devices often have lower latency and more akin to what I think you need. Any reason you want to choose in ear rather than over ear technolodgy?