After months of listening to my D50, I have decided to switch back to a Modi 3, in black. At the time I purchased the Topping D30 and D50, I wasn't being honest with myself about why I didn't like the Modi 3. I convinced myself that I wanted another DAC because of somehow flawed sound, but it was really the silver color that bothered me. The Topping gear that was the right color, but sounded wrong after months of critical listening. I'm certainly not immune to creating flawed rationalizations to justify the things I want in life, and aesthetics are important, but so is sound quality, and I want both.
The Modi 3 resolves minute mid to high frequency details that turn into clicks and mush in the D30 and D50, and outputs tighter bass. I have substantiated this with back to back, SPL-matched testing. The mid to high frequency issues in the Topping DACs typically occur in the processing of lossy files, but not lossless. Also, the timbre of various instruments sounds more like the real thing through the Modi 3. The D50 also experienced some minor RF interference issues that weren't a deal breaker, but ultimately annoyed me. The Topping DACs are okay, but ultimately did not meet my expectations. YMMV.