Which MicroSD-card-speed is necessary for storing music on Lumia 640?

[Windows Central Question]

I want to use my phone as a music player, so I need to expand it's memory.
But how fast does the Micro-SD card need to be (read & write-capacity)?

 

[RumoredNow]

It's not just music. What about photo's Video, etc.? What about Apps stored to SD?

I respectfully suggest your phone has a modern card reader in it and deserves a modern card, Class 10 or UHS 1. Get a reputable brand from a trusted merchant, preferably a brick and mortar store.

Many "deals" on eBay, Amazon, etc can be less than what they appear.

When you get your card, test it with this utility and if it does not meet the minimum standard for that class, return it for a refund.

http://www.heise.de/download/h2testw.html