I had a week to test the Sennheiser cx 400BT (got it for $130) and Technics AZ70 ($160). Both were spectacular.
Packing/case - Az70 wins this one easily. Packing you only care about for 5mins then you put aside & never look at again. Therefore I don’t put much stock into the packing, but Az70 definitely feels more premium. Case is important. Az70’s case is higher quality. Sennheiser is good too but looks cheap next to Technics one. Both get the job done so it probably doesn’t matter much which case you have.
App - Technics has slightly better app. I like being able to control everything including noise cancellation, ambient sound & volume through the app.
Sennheiser app is much more basic. I like being able to remap the touch controls. That's the only advantage over the AZ70's app.
Comfort - Both are comfortable. I feel like AZ70 would fall out even though they were securely in. They are comfortable over multiple hours while sitting listening to music. Sennheiser feels large and bit clunky in the ears. Between the two, AZ70 is bit more comfortable.
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To test the audio, I used Amazon music HD and only HD songs. I’m pretty sure they are not FLAC unfortunately. Ultra HD on Amazon might be flac, but not many songs have that designation. Most have HD designation.
Bass - Az70 is deep & very clean thump if notes go low with no distortion that you might get on low-quality cheap earbuds. Bass is not particularly powerful so if you want lots of bass, this is not it for you. Most of my everyday music doesn't tend be very bass-heavy so I don't mind it (much of my music is focused on vocals with quite a bit of classical instrumental - plenty of drums but not bass heavy). I listened to Carl Orff's famous Carmina burana (O fortuna) with deep choir, drums, violins, bass, possibly cello too and brass instruments.
Sennheiser definitely has better bass. It is more powerful while still maintaining the clean thump that is on the AZ70 with no distortions. Sennheiser wins this one for sure.
Mids - AZ70 has clear smooth mids. This is where you enter the vocals territory. Mids sound very balanced to me.
Both are pretty equal to me. Sennheiser’s lows & highs are better so you would probably feel that it overall sounds better than AZ70, but to me there is no clear advantage to either/or for mids. They are pretty balanced.
Highs/Treble - Az70 sounds very good at the highs. I chose to focus on “Concerning Hobbit” musical for this one from the Lord of the Rings (lots of mids too mixed in) and some saxophone jazz piece I found on YouTube. Highs are not blurry, but I could have sworn there was minor distortion on some instrument notes. Highs in vocals sounded very clear though.
This is close, but I think Sennheiser has this one. It is possible the soundstage advantage of Sennheiser is why highs sound better. Regardless of the reason, Sennheiser sounds better at the highs. It was most apparent with Concerning Hobbits, which has flute/piccolo/other high wind instruments.
I didn’t make full use of sound enhancement equalizer. If truth be told, I had tough time telling the difference - it was not obvious. For az70, I mainly struck to “Clear voice” preset. It sounded tiny bit better than keeping sound enhancement off, but very subtle difference to me. I tried messing with equalizer but didn’t know what I was doing. Left it alone afterwards.
For the sennheiser, it was even tougher with only the equalizer & no presets. I ended up keeping it at default.
Soundstage - I listened to Beethoven’s Fur Elise and Heart of Courage were used for soundstage. Fur Elise is all piano while Heart of Courage has some drums, bass, violins, the whole shebang. AZ70 is bit lacking here. I also listened to Clarity by Zedd with vocals. All very clear and detailed intricate vocals but soundstage felt lacking compared to the cx400bt.
I don't think this is a fair comparison. Sennheiser is almost in a different class as I go through the same exact pieces I listened to with the AZ70. Heart of courage sounded spectacular -- mids and highs sounded very similar between the two, but the drums and vocals gave advantage to the Sennheiser.
Details - I wanted to separate this a bit from Soundstage. Az70 sounds bit lacking in soundstage relative to the Sennheiser l, but I don't want anyone to think it is missing in details or clarity. No, it is very detailed and you can clearly distinguish between different instruments. I listened to Carl Orff's Carmina burana (O fortuna) once again. It was spectacular.
In direct comparison, Sennheiser definitely seems to be bit more detailed & dare-I-say polished. It is almost neck-to-neck though. I had a tough time telling the difference. Their sound signatures are slightly different.
Features - AZ70 wins here. It has ANC (cx400bt does not). AZ70 has sensor to auto-pause on removal (cx400bt does not). It has ambient mode (cx400bt does not). For me personally, I have no intention of ever using ANC, and I don’t care about auto-pause on removal. I do miss ambient mode though. I wish it had ambient mode..
Sennheiser is a $130 earbud ($30 cheaper than AZ70). It’s obvious to me they didn’t want to overstep into the MTW2 sales, which is why they removed all features including even IPX4. I’m surprised they offer 2yr warranty.
Overall, Sennheiser cx400bt has better sound easily. But you get no features.
Technics AZ70 is bit more comfortable and has full features. But bit higher cost - probably $30-40 more.
Since I don’t need ANC, I’m going with Sennheiser cx400bt. Again, I wish I had ambient mode & I would expect IPX2 at least for the $130 I’m spending. I don’t care about anything else it’s missing.
I do wonder if there are better more comfortable ear tips available out there to make the cx400bt more comfortable. If I can get that to improve, it easily wins this one matchup.
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