Sennheiser HD600/650. It’s hard to decide on which is the best, but I think the 650 is more enjoyable from a casual listening standpoint, while the 600 would be better suited for mixing/mastering/reference. These 2 headphones are some of the most important audiophile cans that have ever been released. Learn more:Sennheiser HD600 vs. 650!
The MrSpeakers Aeon Flow. Wow. Perhaps the finest example of a closed back that I’ve ever heard. It has an openness and spaciousness about it that’s truly stunning. It actually reminds me a lot of an open back. Paired with a Chord Mojo? Forget about it. One of the best listening experiences I’ve had. Learn more:MrSpeakers ÆON Review
Oppo PM3. One of the most relaxed and detailed headphones I’ve heard, the PM3 combines everything that makes a headphone great: Comfort, Build and Sound are all exemplary. There’s really nothing this headphone does wrong. Learn more: Oppo PM3 headphones review
The mid-range on both is very revealing, and I couldn’t discern a huge difference. Perhaps the 400i is a bit more forward around 3-4k. You may notice instruments and vocals have some extra zest.
Build. I think the PM3’s are more durable overall than the 400i’s. You should know that the newer model 400i’s have QC issues with the headband Yokes. The old model that I’ve demoed on countless occasions is still in great condition over at Audio Advice. The PM3’s feel more rugged in your hands.
Comfort. I would these two headphones are kind of similar with regard to comfort, but if I had to choose, I’d take the PM3 over the 400i. Sometimes the 400i tends to slide downwards onto the tops of your earlobes and it can get annoying after awhile. The PM3 by contrast has an almost perfect comfort level over long periods of time. It just tends to snuggle with you like that special someone. 😛
Bass. The bass on the PM3 is pretty much a flat line. There’s a really nice amount, but it doesn’t ever become overbearing. It doesn’t roll off, but it’s also not V-shaped like the bass head variety cans. By contrast, the bass on the 400i does roll off more, but it’s still very articulate and detailed. Depending on your tastes, you may like one more than the other. For me personally, I enjoyed the bit of extra bass on the PM3.
Treble. Another difference is the treble. The PM3’s rolls off quite a bit. I would say for a lot of people this will be a concern. For me it wasn’t for whatever reason. I really enjoyed the relaxed nature of the treble. It’s a welcome change from the overly bright nature of a lot of other headphones. Yes, the PM3 tends to be a darker sounding headphone with a similar treble to something like the HD600. The treble on the 400i is also fairly relaxed, but perhaps a bit brighter than the PM3. You’ll notice a little more sparkle out of the 400i.
Amplification. This is a big one. The 400i’s come in at 93dB of Sensitivity which essentially means they will need quite a bit of power from an Amp to reach peak loudness (The standard is around 110dB). They are not efficient at all. Related:What is Sensitivity in Headphones? By contrast, the PM3’s have 102dB and are very efficient. You can plug them into your phone and they’re going to sound great. That’s not to say an Amp/DAC won’t help though. I tend to recommend Amps to most people because it’s a sound investment (no pun intended). If you have a good amp, you can pair it with many headphones as you upgrade and try more. That said, it’s mandatory that the 400i’s be paired with one. With the PM3 you can get away without it. Check out my big article on it:What is a USB DAC?
Portability. Because the PM3 doesn’t need an amp and it’s closed back, it’s much more portable than the 400i. Being that the 400i is open, it tends to leak sound which will bother others around you. I would never use the 400i in public, but I would carry around the PM3 with me. The 400i is more of a studio headphone and 95% of the time that’s where it will dwell. Learn more:Closed back vs. Open back headphones.
Here I compiled all of my impressions of the 400 series since 2017!
Lachlan’s PM3 Video Review
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I really love the sound of the 400i, but I would only purchase a pair if I knew it was one of the older models. HIFIMAN is bound to improve upon this issue in the future, so stay tuned for that and definitely reach out to me if you have any questions about it!
Stu is determined to help you make sound decisions, and strives to deliver the best and most in depth content on the internet! In his spare time, he likes to fish, paint, play guitar, pray, rap, make beats, take photos, record videos, graphic design, and more. His sense of humour, coupled with a knack for excellence and strict attention to detail are what allow him to stand out in an crowded industry.