Apollo has an unconventional sound signature with fuller lower-midrange and recessed upper-midrange, which makes it fall in the fuller and warmer side of neutral but with some treble emphasis that restricts it from sounding dark. It’s a headphone made for an extremely relaxed and laid back listen than a reference-neutral headphone that targets neutral accuracy of tonality and timbre. It has a bit of roll-off in sub-bass, fairly neutral mid-bass, full and fat lower-midrange, recessed upper-midrange without much ear gain, neutral-warm lower-treble and airy upper-treble. Even though Apollo is airy post 12.5kHz and the treble does extend till the upper end of audible FR, it still comes across as a warm headphone because of emphasised fuller lower-midrange and lack of proper ear gain. The airy upper-treble however adds the much needed sparkle and energy into the signature.
Let’s dig in deeper…
Bass – Apollo has a bit of sub-bass rolled off down low, so don’t expect much rumble here. The mid-bass however is fairy linear and neutral and as a result, bass punch and slam are quite neutral and the bass presentation isn’t too upfront/in the face. That is actually a good thing for Apollo’s overall tuning. Otherwise, it would’ve made for an extremely warm and boomy signature because of its unconventional midrange tuning.
Midrange – Apollo’s midrange is tuned quite unconventionally. I can see some liking it while it being a deal breaker for others. It has a thick, fuller, north of neutral lower-midrange and recessed upper-midrange which lacks the required ear gain for accurate tonality, timbre and forwardness of instruments. Because of this kind of tuning, it sounds muddy, hollow as well as honky. Fans of thick and fuller style of lower-midrange tuning might enjoy Apollo but people who like a more neutral and reference approach of headphones like HifiMan HE400SE/Sundara, Sennheiser HD600 series or Focal Clear/Elex, will find vocals and instruments lacking the required clarity, definition, forwardness, bite and crunch for accurate tonality and timbre. This is not a versatile headphone as not all songs translate equally well on it and all of Apollo’s tuning actually makes for a little too laid back of a listen. People who like tonal accuracy will definitely be left wanting more.
Treble – Apollo has fairly neutral lower-treble but north of neural, airy upper-treble. The airy upper-treble adds the required sparkle and excitement into the otherwise warm signature but Apollo still comes across as a warm headphone overall because of its midrange tuning.
Technical performance – Apollo has a relatively intimate soundstage but one that is able to form a good sense of space around the head. Imaging performance is compromised because of the upper-midrange dip which lessens instrument definition. Clarity and detail retrieval are decent but are sadly defeated by much cheaper headphones like HE400SE and Sundara as well as their own P-II and Aiva quite easily.
Sendy Aiva (reviewed here) – IMO, Aiva looks more premium and has the better overall design. Sound wise, they are polar opposite headphones. Where Aiva is a thinner sounding bright headphone, Apollo is a warm sounding headphone with thick and fuller lower-midrange. Aiva has better bass extension and slightly better feel of bass rumble and punch whereas Apollo has a sub-bass roll-off and hence lacks the rumble. Aiva has a more linear, neutral lower-midrange whereas Apollo has a boosted lower-midrange and is much fuller and intimate in its presentation. Aiva has more ear gain/forward upper-midrange which enables stronger instrument definition. Aiva is also much brighter in treble, especially upper-treble, and has better treble extension. Because of all this, Aiva is a much more energetic and revealing headphone whereas Apollo is an extremely laid back listen. Aiva has a slightly more open soundstage and better detail retrieval.
HifiMan Sundara 2020 – Compared to Apollo, Sundara 2020 is a much more neutral headphone with better sub-bass extension, a very neutral lower-midrange, strong instrument definition because of ideal amount of ear gain, better balanced and more neutral treble presentation with better upper-end extension. All this results into a very accurate reference presentation that highlights the natural tonality and timbre of instruments. Sundara 2020 not only has a better soundstage and imaging performance but also better detail retrieval and resolution than Apollo.
I’ve reviewed quite a lot of Sendy/Sivga headphones. I quite liked their Phoenix and P-II, and even though Aiva was a little bright for my taste, it took EQ quite well and sounded even better when you turned a bit of that treble brightness down. Apollo does not follow any crumbs laid down by any of their previous models. Where Apollo does really well with build and comfort, much better than most of their previous models, it sadly leaves a lot to be desired in its tuning and technical performance because a lot of headphones much cheaper in price are able to hit above what Apollo offers. Apollo isn’t the most versatile headphone and likability of its warm, thick and full lower-midrange based signature will highly depend on one’s liking and preferences. I personally think Sendy/Sivga really need to up their game in the tuning department and not just solely focus on making headphones that look pretty, which they already know how to do well. They really need to keep track of the competition, at least successful models of major brands like Sennheiser, HifiMan, Focal, etc. to gauge where the current competition is at and where it is heading. Much cheaper headphones like HifiMan’s HE400SE, Sundara, Sennheiser’s HD6XX and HD560S punch much above their weight and offer exceptional value for money. That’s the competition a headphone priced $500 first needs to beat in order for its pricing and value proposition to hold up. Sadly, Apollo’s doesn’t.
Gear used for testing and review.
- DAPs – iBasso DX240 | HiBy R5 Gen 2
- Desktop – Universal Audio Apollo Twin | Drop THX AAA 789 Amp
Artists I like and listen to.
- Rock – Foo Fighters, Linkin Park, Switchfoot, Imagine Dragons, Daughtry, Green Day, MuteMath, X Ambassadors, Dave Matthews Band, Vertical Horizon, Our Lady Peace, Lifehouse, Fall Out Boy, Breaking Benjamin, Muse, ACDC, Audioslave, Rage Against the Machine, Biffy Clyro, I Am Giant, Normandie, Paramore, Slash & Guns N Roses, 3 Doors Down.
- Pop Rock – John Mayer, Coldplay, Paul McCartney, James Bay, Hunter Hayes, Niall Horan, Keith Urban, The Bros Landreth, Bryan Adams,
- Progressive Rock/Metal – Porcupine Tree/Steven Wilson, Karnivool, Tool, Dead Letter Circus, Periphery, Lamb of God.
- Pop/Soft Rock – Ed Sheeran, Adele, Taylor Swift, OneRepublic, The Script, Gavin James, Magic Man, Maroon 5, Bruno Mars, Charlie Puth, Dua Lipa, The Weeknd, Oasis, Panic! At the Disco, TwentyOne Pilots
- EDM – Chainsmokers, Zedd