on my K50, I managed to connect 1TB SSD drives via USB, but my 4TB SSD drive is not recognized via USB, is this normal?
Hi
It’s been some months, so did you manage to get it to work? Or ist it only possible to connect one external drive via USB?
best regards
Lefreck
Hello, I didn’t look any further… I kept the external USB SSD for Roon backups and installed an 8TB internal SSD in the K50 (Samsung PM893).
Besides, it’s practically full; I’m going to install a second one. 
Yes, it is quite possible that an attached USB is not recognised.
There are a number of factors.
Antipodes Audio music servers use Linux, any drive that is attached should be re-formatted in exFAT as this format is cross platform compatible with Linux, Windows and macOS.
There is potential that the attached external USB exceeds the power requirements that are available.
There are a great number of external USB manufacturers that do not list Linux compatibility.
What we have always said is use your network for back-up and file copy.