Nice, mind elaborating on the differences you hear?
I'll try!
The 30's sound warmer, and with more presence and definition. The soundstage is not as intimate as the 10's, or what I'm generally used to I'm used to, and I'll need to adjust to that. However, the sound isn't just pushed back a little bit, it gains space and depth. The 10's have decent enough stereo imagery and separation of the instruments, but the 30's take it to another level entirely.
The bass on the 10's is somewhat lacking, but what little you do get is actually quite nice. However, The 30's deliver what the 10's only suggest, the bass has depths and presence. I was concerned the bass might actually be a bit too much, going by some comments I've read, but it's not. It's not over done, and I an even imagine some bass heads might not be satisfied. I am though.
The mids are clear and have a lot more definition and presence than on the 10's. The 30's are definitely darker sounding than the 10's, and sometimes the mids can sound a touch laid back, but maybe that's just me not being used to the way these present the sound.
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The highs are meant to be a bit lacking on the 30's, from what I've read but not for me. The overall warm signature could mean they don't sound bright enough for some, but the highs come through just fine for me. Detail retrieval is good. At one point I could hear a bit of hiss coming from my Fiio M6, which is known for being very quiet. Turns out it was WiFi noise that the 10's don't pick up.
Althounding a bit dark, the 30's are not at all dull sounding. The 10's aren't as dark, but can sound a bit dull and ordinary. (especially compared to the 30'). I feel bad saying that though, because the UMPro 10's are very competent, and I will still have a use for them.
I'm not normally a fan of darker sounding headphones, but I'm liking these. They sound smooth without being too laid back, and I don't think fatigue will be an issue. The 10's are also very non fatiguing.
When I first tried the UmPro 10's, (and UM1), they were a little bit underwhelming, but the sound soon grew on me, and the more I listened, the more I liked them. I'll be interested to see whether I have a different impression of the 30's over time.