Closer Examination

The Symphonium Helios ships with one Altalune Audio Nova cable in the source connector of your preference—2.5 mm TRRS balanced, 3.5 mm TRS single ended, or 4.4 mm TRRS balanced. This review unit came with the two balanced cables so please don't misconstrue things based on the photos above. The important thing to note is that the cables, no matter which one you go with, are identical once past the source plug in its black metal housing. We then come to what is one of my favorite cables to date in the form of a highly pliable, nice-looking, and extremely functional unit with low impedance and zero microphonics. It is composed of 26 AWG 6N (99.9999% pure) OCC (Ohno Continuous Cast) copper, braided into four strands in a Type-2 Litz configuration with a clear sheath on top. The cable then has a splitter with an actually usable cinch—another rarity with IEM cables in 2022—before we reveal a true unicorn, in the form of no pre-formed ear hooks or memory wire on the IEM side! Instead, Symphonium Audio is allowing for this relatively thin and easily re-shaped cable to be worked around your ears and used with the cable cinch, regardless of whether you route the cable down the front of your body or the back. The IEM connectors themselves are standard 0.78 mm 2-pin plugs hosted on an extending housing that is better suited for IEMs with recessed connectors, and have blue/red rings on the plastic section underneath to help indicate the left and right channels,respectively. All the metal plugs are gold-plated, for additional oxidation resistance.


The first thing that came to mind when I took out the Symphonium Helios IEMs from the case was "Wow,these are large and heavy". Anyone considering these should be absolutely aware of the possibility they might be too big to you, and unfortunately it's not a case of being big simply for the sake of it. As such, there is no room to shave off in a future update, and all the intricate circuitry is being put to good use too. Given the start-up nature of the brand, I was also pleasantly surprised to see something other than the usual resin shells with an aftermarket face plate applique glued in place. Instead, we get fully machined 6061-T6 aluminium alloy that has been tempered and treated to produce a high strength, high durability material that seems perfectly suited for durable IEM shells that don't pick up dust or fingerprints. Once again I must note that this review unit has made its way through a review tour and the fit/finish at this time may not be completely representative of a brand new set.


The shells get a black finish to fit with the minimalist aesthetics ongoing throughout with the Helios, allowing for plenty of room on the effective face plate here for branding in the form of "Symphonium" and "Helios" along the sides of each of the two shells that also act as left/right indicators. Notice the dominating triangular form factor here, with rounded corners that help to better fit in the ear concha, the side view shows better exactly how large/thick these shells are. In contrast to the cable plugs that benefit from recessed connectors here, we instead get a second extension to where it's not the most elegant implementation if I say so myself. While there isn't much possible here, perhaps going with a cable that had non-extending housings would have been more ideal—even if the cable by itself costs $119! That said, I appreciate how well these shells have been put together with no telltale signs left from the hand assembly employed. The nozzle is machined out of the same aluminium alloy and relatively long at ~7 mm and steep to try and get around the fit issues from the shell form factor itself. It is ~5.75 mm in diameter on the outside and have a metal mesh on the end to help prevent contaminants from entering the acoustic chamber.


We saw before how two types of silicone tips in three sizes each come with the Symphonium Helios, and seen above is the size M version of each on the right channel. I had to stretch the bore slightly to fit over the nozzle, also note there is also no retaining lip/notch to help keep them in place. Instead, you have to push them in all the way and allow the compression/expansion forces balancing out to prevent the tips from coming loose. The AZLA SednaEarFit tips certainly have a larger bore opening, but still I suggest you try them all out for the best-possible fit, including different sizes for both sides if your ears are not equally sized or shaped. Regardless of which tips you go with, the next step is to connect the cable by carefully identifying the matching channels and then pushing the 2-pin plugs in place. There are no pre-formed ear hooks or memory wires to consider here!


Now, simply connect to the source of your choice, and here I am showing off the Hidisz S9 Pro portable DAC/amp which arrived here unsolicited. As such, it won't be reviewed separately but I decided to give the company credit by briefly covering it in this review. The Symphonium Helios is more demanding on the source than just about any other IEM I've tested to date, and the two balanced cables here meant I had to use a balanced source too. The Hidisz S9 Pro provides both 3.5 mm SE and 2.5 mm balanced outputs, I used the latter here as seen above, which in turn is connected to my PC/laptop via the provided Type-C cable. It also comes in handy on the go, which is how I usually prefer using IEMs anyway, whereby the Hidisz S9 Pro + Symphonium Helios combo works great with my phone too. Alternatively, you could just skip the phone/S9 Pro and go with a dedicated DAP such as the HiBy R5 (Gen 2) we reviewed previously.