Some months ago, I bought this Audiophonics DAC-Streamer and I am pretty happy with it as nice streaming DAC with an integrated Roon Ready Raspberry Pi bridge.
You rarely find in a consumer grade DAC exchangeable OP amps, but here it is the case. Standard issue is a pair of JRC 5534 OPAs, that sell for less than a 1 $ a piece.
After diving into the subject of audiophile OPAS I decided to try the Burson V6 single discrete OPAs. Installation is plug&play and was done in less than 15 mins as the Streaming DAC is easily serviceable.
Listening session started with my favorites from jazz, blues, folk with a focus on voices and instruments and their presentation on the virtual sound stage.
I was very surprised how much better the separation between instruments appeared, the voices came closer to the listener and some sibilance issues were reduced. I had to angle the speakers a little wider because the sound stage got very sensitive to movement.
All in all I am pleasantly surprised what $90 can do. Second best investment after HAF room correction. My Nubert Nuvero 140 speakers are still state of the art and respond very well to such changes.