I literally just bought this from one of the certified dealers (as listed on Topping's website) from AliExpress for $250, and then this drop came.... RIP
Anyways, I came from a Modi 2 + Vali 2 and the difference is night and day... The D50 really is a very good DAC. I kept reading from multiple forums that "all DAC's sound the same once you get around $100", and honestly that is the farthest thing from the truth. The amount of detail and extension into both extremes is just absolutely stellar on this DAC. I currently have it paired with a CTH Amp, and my headphones are the TH-X00, however even with my Vali 2, this DAC extended much further than the Modi 2 ever dreamed of... In addition, it opened up the mid-range a bit, so really, it is a very significant improvement across the whole frequency range. The part that surprised me the most was the sub-bass extension. Listening to Manslaughter by Savant, there is a sub-bass wobble in the part leading up to the chorus that I had never heard before, even in the car, or with any other headphone (K712, HP-150, T50RP, etc.). It appears the limiting factor here was the Modi 2, but the D50 really just opened everything up. It also did very well with one of the most difficult artists I've come across for audio setups to properly reproduce (IMHO): Late Night Alumni. For this reason a lot of my testing with new DAC's/amps/headphones are done listening to her because she has the craziest upper range that's super delicate and nuanced, yet completely effortless, mesmerizing, and even eery. For this reason, setups that are too bright or just not the best tend to murder your ears and when it's off, it's quite noticeable. Listening to Every Breath is Like a Heartbeat on this DAC is just magical. It reproduces her voice so well and picks up every little detail. It's so rich yet so airy. I will admit it did get close to being a little too bright for my ears when paired with the Vali 2 (I'm quite sensitive to the upper region), but just how great it sounded kept me listening regardless! When paired with the CTH, it is toned down a bit in the brightness, but that doesn't take away from the detail. In fact it sounded far more natural, and it was as if she was in the same room. This second pairing appears to have a more laid back signature than with the Vali 2, which in comparison sounded a bit more artificial. That isn't bad per se, because actually overall the Vali 2 did sound quite fun and sparkly with the D50, but I think that is due to some upper range coloration.
This is a very hot DAC, however, so unfortunately, when paired with the CTH, it's a little too much power for my poor TH-X00. The volume has to be kept super low on the amp, and when the amp is turned anywhere from 0 to 11-12ish o'clock, there is audible hiss and static in the right channel. In order to mitigate this I had to attenuate on the D50 very significantly, but the nice thing is, even when attenuating to -32 db, it is still almost the same clarity and detail as when not. This allows me to get the CTH to around 2 o'clock, thus eliminating the hissing. This is a real feat for this otherwise obscure DAC that not really many people talk about. Overall I'm very impressed and can't praise it enough.
As a side note, I also picked up the Jameco Linear Power adapter (5v 1a) on Amazon and it fits perfectly and does a great job. Even with a switching power adapter and the supplied USB power cable, it still sounded quite good, so you can go either way really. I didn't notice too much of a difference here.