Hard to tell from your post what you mean by "upgraded" and exactly how or if you are using the micro-rendu. But if you are using the original Oppo 103 DAC section you could easily improve your SQ by several steps with an external DAC. In fact, using the software available with the micro-rendu you could probably bypass the Oppo entirely. A next step might be getting your music out of or running through the computer, where it is subject to degradation, even if you use the computer to control the process.
The Oppo is like a fine Swiss Army knife. It does a lot of things, but none so well as a dedicated single use device.
The Oppo is like a fine Swiss Army knife. It does a lot of things, but none so well as a dedicated single use device.