Got M0 Pro for a few days and I am very happy about it. Direct drive IE900 via balanced adapter sounds very good. It has sufficient power to drive less demanding IEMs. Sound is not as expanded as high end DAPs that is for sure but not lacking too much. Lows are deep for the price and it can slam (with easy to drive IEM). High is polite and mid is a bit forward, making stage a bit narrow. Guitar string sounds very live like. Tuning is neutral, not V shaped. Detail is above the same price range DAPs. Dynamic is good if IEMs are not too demanding. Even though it is not as good as DX300, WA8, let along desktop DAC/AMPs. it is not too far behind from portable DPAs. I think it is very good considering the cost of M0 Pro. I also have a M0, and M0 Pro is light years ahead. I use the M0 mainly with TWS earbuds for exercise. When working and not too serious about the sound, I would use M0 Pro.
One drawback is M0 Pro’s line out. It sets the output to maximum and making sound clipping and coarse. When driving it with WA7, it clips so much, it is not a very enjoyable experience. I do not know if it is the inter connect cable but I doubt it Is.
Overall, I think M0 Pro is very good for the price and it is very suitable acting as an entry level DAP. If you no longer pursuit summit level of sound, and is willing to settle for less, this is the DAP to keep.