Separate DAC or continue using the Oppo UDP-205

Hello,

  I have all my music on a hard drive in FLAC.
I am a using Sonos Connect, Optically connected to the Oppo. From the Oppo (RCA'S out) to a Primaluna Dialogue     Preamp. The Amps are 2 Primaluna HP's. Martin Logan Theos speakers. I have rolled mostly all the tubes, and absolutely love the sound. Family and friends also love the sound.

 My question is, Should I continue going through the Oppo, or should I get a separate DAC? Nothing to crazy in price.
I have seen these things go for thousands, and thats fine if you can swing it. I was thinking around a $1000.
But, would it change the sound or would it pretty much be the same? In other words, is the Oppo that good at what it does?

 Since we are always tweaking our systems to make them sound better, I thought I would ask all of you first, before calling the salesman. I also have thought about  getting a turntable. But I gave away all my albums many years ago.
Buying a turntable, buying albums, taking care of all that stuff. Not really what I had in mind. I would like to keep it fun, and simple.

  Thanks