Concise and well-put, Stephen Hornbrook's review of the awesome Oppo PM-3 is well worth the read.

“We recently gave another Oppo product, the HA-2, perfect marks, so to do so again seems odd. Yet I feel even stronger about the Oppo PM-3’s perfect score than I do about the excellent HA-2. The Oppo PM-3 planar magnetic headphones are scary good. Previously my go-to recommendations for closed back headphones were the PSB M4U, NAD HP50, and Sennheiser Momentum. The Oppo PM-3 outshines them all and will be one of the most confident product recommendations I have ever offered. They are versatile as they can be driven directly from a smartphone, but will benefit from quality amplification so users can squeeze every bit of performance from these amazing headphones. If you don’t need a closed-back headphone, the Hifiman HE-400i delivers better sonic performance but only with better amplification. If looking for more flexibility with sources and listening environments, the Oppo PM-3 is the clear winner. Very highly recommended.”

Source: Oppo PM-3 Headphones Review

For reference, my review of the PM-3 can be read at Headfonia.