The soundstage is fairly good but it feels a bit cramped and narrow when vocals and instruments are playing together in complex passages. Stereo imaging is mostly precise and clean, but again, the lack of transparency of the mid-range affects it negatively. So those aspects are good with the flagship Sendy. The precise imaging provides a nice focus, and you can track down every element of a song easily. However, since the mid-range is not clean/transparent enough, the air and space are not on a high level in that particular area.
The balance of the headphone is not ideal for reference listeners. It instead has a fun signature as I mentioned above. So coherency is not a strong point of the Apollo. The transition from the mid-range to the treble area is one of the problems. The mids sound a bit veiled, whilst the treble area is crisper, and the bass has better resolution and texture. The result is an unbalanced presentation and congested mid-range. So coherency-wise the Apollo is not the best choice. But it’s certainly fun-oriented.
One positive aspect of Apollo is good detail retrieval. With a sufficient desktop setup, almost every detail is audible in a precise manner. I just wish the mid-range clarity could be better.
HD660S is one of my favourite headphones below 1000$ mark, and for good reason. Comfort-wise there’s not much difference there but I have to say the Senn is lighter so it fits better for long durations. Build quality is better with the Apollo with wood and aluminium parts.
The HD660S has impactful bass, but the Apollo utilizes the planar magnetic driver and gives more kick, pace and decay. It recovers faster in the bass with excellent texture and body. In the mid-range however, the Sennheiser is much cleaner and more transparent. It also has a better resolution here.
Treble is good in the Apollo and so in the Sennheiser, but I think the Sennheiser has better extension and transparency. The sound stage performances are identical but the congested mid-range of the Apollo hurts the overall imaging. So I think the HD660S is more audiophile, whilst the Apollo is more fun and warm.
Sivga is a sister brand to Sendy Audio, and I just recently reviewed their latest SV023, which is a dynamic headphone. They share similar headband designs and build materials. The SV023 is more comfortable thanks to dynamic drivers being lighter.
The SV023 is a good example of clarity, resolution, balanced and technicalities. The Apollo leans on the fun side of things with a full-bodied, toe-tapping signature, especially in the bass. The SV023 has more resolving mids and a cleaner presentation with better transparency. It’s flatter, more cohesive, and more refined.
The Sendy Audio Apollo is a very good headphone in terms of build, comfort and accessories, with a delicate and premium design. It has excellent build quality as well. The sound is very impressive in terms of bass, but I got a feeling that if the mid-range had been more transparent and crisp, this would make an excellent budget-friendly planar headphone.
While I still think that it has better value than the flagship Peacock, I wanted more in terms of coherency, transparency and sound-stage. I’m so impressed by the bass performance (as good as the Hifiman Edition XS, if not better), but the mid-range resolution needs some tuning and since it has a fantastic tonality, I think this concept has a lot of potential.
I think the approach is suitable in terms of market demands for design, build quality, and accessories. I’m sure the sound tuning will be improved with time. Yet, if you listen to RnB, Pop, Rap and EDM, you’ll be very impressed by the fantastic bass response.