I also own the Oppo PM-3 and agree that with the AR, both are neutral. To my ears, it sounds like vocals are more present in the Oppo vs the AR. I auditioned the AR for three days straight, trying different cans (DT1990, Oppo PM-1, AQ Nighthawk/NightOwl both Carbon, Fostex TH-900), and I changed three amps Marantz, Teac UDH-505, Triode tube- I tried hard to get a feel for their characters and combinations. My point is, I kept getting a very in-head sound for vocals, like with Sennheiser, whereas other headphones sounded more spacious, putting vocals and instruments in front of the head. I even had an issue with panning on the AR where the sound would pass from ear, to in-head, to opposite ear, where as the other headphones had the sound pass from further outside my ear, to center in front of my head, to further outside opposite ear.
In your experience, is this meaningful? I felt like front to back depth was lacking, even spaciousness of the AR unless I used a tube amp.
Did you get a similar sense of space?
I also agree that the neutrality is there, they did remind me of my PM-3 also, but I like my PM-3 better as per my ears/taste.
What also killed it for me was the lack of body in vocals for the AR, which if I only used when mixing and mastering, might make my tracks more vocal heavy in the finished product.
I suppose I could use the Audioquests, Fostex, or any Sennheiser HD6 series for music enjoyment, and then keep the HR and my PM-3 for critical listening.
Can you see yourself relaxing to the AR? And where/when/how would you use them?