Do I need a streamer?

Streaming devices, with or without an internal DAC, seem to be very popular these days, so I am wondering if I am missing out on something.  I have Audirvana on my iMac that streams Tidal and music from my 8 TB external HD.  My iMac resides next to my audio rack and I connect my iMac via an optical cable (Fibbr) to my Aqua LaVoce DAC.  It seems to me that my iMac and external HD take the place of a streaming device.  Am I missing out on something other than convenience?  My external HD was a few hundred bucks and streamers a whole lot more.  The sound of my system is fantastic.