I got the brown case today and have finally started hauling my Plenue D around. I was too paranoid to lug it around so I was using the Fiio X1. I absolutely love the form factor. It's so small fits great in my pockets. I was using the Sendiy M2's with it but it just didn't sound right so I went with the Monk +'s and they sound lovely paired up.
As for the leather case. I can't say I'm impressed with it. Although fit was top notch, the quality seems a little sub par, especially since I paid $34 for it and had to wait a bit for it to ship from Korea. Anyway, it achieves the result of protecting the Plenue D.
What is "sub par" about the case? It's very well made, I don't see anything REALLY wrong about the quality being crafted out of high grade leather that will last for years, is more durable than most plastics or rubber or silicone thinly cheaply made cases. I don't really agree. It's a match made perfectly and a well designed case that will protect the PD very well.