If you have a spare phone or tablet, you can hook it up to K7 and stream your audio that way. For example in android I am using YAACC and UAPP app to stream from moodeaudio (audio streamer and player running MPD) to my phone.

Basically, after you install media server plugin on synology nas, it will show up on the apps I mentioned as UPnP/DLNA server. With the phone/tablet connected to K7 you can serve your audio files to it. Try this with your phone without having to buy K7 first. With an app like UAPP, you can access your NAS via ftp, sanba, or webdav interface and serve your files that way too.