That's a nice TV, plenty of connections - I like the USB connection. Unfortunately, as you said, the only audio out is digital. Bit disappointing that there are no RC/phono outputs.
However, when you say speakers, do you mean connected to a hifi or AV receiver etc., or were you able to connect speakers directly to an older TV?
I've never put the TV through external speakers, I prefer to connect the source eg. DVD player/recorder, freeview recorder or Sky box (now replaced by a Freesat HDR) through an AV receiver and good quality speakers (either side of the TV, not in a corner) using phono connections. Then, when watching a DVD etc. we get the best sound. For day-to-day, general TV watching, we find the TV speakers good enough.