1) The old Roku's from several years ago, that still had outputs other than HDMI, will NOT do all the services anymore (example: Spotify). They have been made just about obsolete, unless the only services the customer cares about (or will care about) are still available on the old ones.
The new Roku's, that only have HDMI output, you will have to use an HDMI audio extractor - longshot16 already knew this, that is why he asked specifically about the HDMI audio extractor. It is obviously a newer Roku.

2) As others have said, there are many options from cheap to expensive for audio extractors. And you will need to set the Roku to output 2 channel only.
As I mentioned last year when I went thru this - there are no HDMI audio extractors that will give you a digital audio output (coax/optical) that will work with surround sound on Netflix, Vudu, and others. Because they use "Dolby Digital Plus" and none of these HDMI audio extractors can/will convert to regular DD.