I was not expecting PLUSSOUND to come out with an IEM, let alone a high-end multi-driver hybrid version but then again, it seems to be going that way with quite a few cable makers over the last year or two.
Their new Allegro is no cookie-cutter release. It aims for the top-end of the portable audio dining table alongside big hitters such as Empire Ears and Noble to mention a few.
One of the advantages of being a well-established boutique cable maker when launching an IEM is that is unlikely to come with a crappy cable. So yes, PLUSSOUND has thrown in one of its 4-digit + aftermarket cables, the Copper+, as Allegro’s stock wiring. There is even a little ace card being played on the internal wiring so keep it consistent.
The PLUSSOUND Allegro is a ‘tribrid’ 12-driver per side high-end universal IEM. It uses a mix of dynamic, balanced armature, and 2nd generation Sonion electrostatic drivers inserted into a 3D printed acoustic chamber with a low-profile ‘slit’ in the housing to manage the dynamic driver airflow.
The precise grouping is 2 10m dynamic drivers for the lows, no less than 6 BA in a dual-driver configuration of 2 for the mid-lows, 2 for the mids, and 2 for the mid-highs. The final grouping is a quad-EST driver array, (complete with micro-energizer) for the highs and ultra-highs.
This is all threaded with an advanced 6-way crossover. I have only seen a few monitors with 6-way or higher with the 8-way Empire Ears Odin being one such example. Even the flagship tribrid Viking Ragnar from Noble only uses a 4-way so this is a fairly complex setup.
The Allegro rating is typically low for these types of hybrids at 12Ω impedance and 112 dB @1kHz though you can be sure with that quad-EST driver array it will suck up a bit more juice than you might expect. You can read up on efficiency performance in more detail on page 2 of this review.
There is an important highlight that is often overlooked by both audiophiles and manufacturers and that is the internal wiring of an IEM. Not so with PLUSSOUND.
First, the connectors have been upgraded also with a specially designed and cryogenically treated 0.78mm rhodium-plated tellurium copper 2-pin socket using PEEK insulation.
Second, the Allegro comes with a form of internal wiring called Copper XS, which is in-house designed and is composed of a cryogenically treated Type 6 UP-OCC with their proprietary PS Insulation.
That should provide a good match for the stock cable which is no less than PLUSSOUND’s own excellent Copper+ which starts at $999 in their EXO Series class of cables.
The Allegro’s 3-piece dark bronze polygonal faceplate and gloss black diamond pattern body look stunning, no two ways about it. Every angle in the light throws up a different shade and ambiance from its aesthetic.
Even the stainless steel caps on the nozzle look fresh out of the oven with a very clean finish around its triple-bore exit.
For a bonus point, if you can get the Copper+ stock cable finished with their signature rose gold barrels and hot-stamped metallic heat shrinks then you have a very complementary-looking setup.
It is also beautifully smooth to the touch rather than uncomfortably sharp on the edges with nothing in the way of ungainly finishing such as jutting screws or large gaps in the seams. Even the slim and long vent for the dynamic driver is tastefully slotted at the rear of the main body shell making it almost invisible to the casual eye.
The Allegro shells are on the larger and heavier side though which is unsurprising given that they are 7-axis CNC milled from a relatively thick block of aluminum for both plate and body.
As a comparison, I would place the Allegro weight roughly on the same level as the Noble Audio Viking Ragnar shells which are also made from a block of aluminum.
Comfort & Isolation
I suspect the Allegro might be hit-and-miss with some for precise fitting and comfort levels. My own personal experience varied depending on the selection of the tips due to the relatively short and fat nozzle on the main shell.
That lack of length will mean the weight of that aluminum material might press somewhat more into your ear’s concha basin and surrounding areas compared to longer nozzles as you try to get a tight fit.
For some that might feel increasingly uncomfortable over longer periods but again that depends on the precise shape of your ear and the tips you use.
The Allegro comes with 3 types of branded tips in small, medium, and large sizing and some of these are my favored types, in general.
This includes Comply foams, Symbio W hybrid tips, and a set of generic single-flange silicone tips that turned out to be my preferred pairing out of all of them though at the cost of some additional pressure on the ears.
The foams pushed the Allegro housing reasonably well out of the ear and for a vented hybrid in-ear monitor it did not do too badly in terms of the level of passive isolation. I would place it on par with something like the Viking Ragnar’s foam tips as a point of comparison.
The Symbio W tips do much better in keeping the shell away from the furthest recesses of your ear but they are a little more unyielding in terms of conforming to your ear canal so I found them slightly less comfortable than the foams. The passive isolation performance was better than the foams though.
The single-flange silicone tips were my preferred choice out of all the stock tips. Yes, of the three they allow the Allegro shells to come deeper into your ear but the flip side is the comfort in the canal was superior to the foams and Symbio W tips.
The passive isolation performance is just a shade behind the Symbio W tips but better than the foam tips for my ears. They also produced the cleanest audible performance from the Allegro tuning, and I suspect getting the short nozzle closer to the canal itself is a factor in that outcome.
The Allegro stock cable is PLUSSOUND’s Copper+ from their EXO Series which is a $1k cable in its own right and one which we rated quite highly in its own separate review back in 2021.
The Copper+ is a 4-wire high-purity 24AWG gauge UP-OCC copper cable with a fairly complex coaxial geometry and unique handling properties compared to more traditional Litz-type aftermarket cables.
The core of the cable is UP-OCC copper 24AWG in a single-twist Litz configuration. Then you have another outer layer of UP-OCC but this time they are 5-strand bundles in a Litz configuration.
In between the new copper Litz geometry, a second clear type layer of PS insulation isolates that core single twist from the 5 strands twisted bundle outer layer. You then have a main PS insulation jacket wrapped around that outer UP-OCC copper 5-strand twisted bundle.
The Copper+ uses PS Shielding just under the outer PS Insulation to protect the signal from potential EMI interference as well as operating as a ground layer. So, that means the Allegro should stay free from interference noise from WiFi and BT during use with DAPs.
A slight drawback of the coaxial design is the relative stiffness and slightly higher than normal level of microphonics during use. It’s not a deal breaker for me but it does handle a bit differently than PLUSSOUNDS non-Plus designs.
This particular sample comes in a twisted design but you can also get it in a braided version. We have the braided version of their award-winning Hybrid+ here and it also has some pros and cons. It is a little bit thicker but quite as stiff and thus easier to roll up than the twisted Copper+ when in use.
The finishing is excellent. PLUSSOUND offers some of the strongest builds in the aftermarket cable business for my money. You will not see any unsightly memory heat shrink or exposed strain relief. Everything is neatly tucked into the hot-stamped metallic heat shrinks with the barrels screw-locked which I much prefer over internal glue.
PLUSSOUND has a picture of the silver-finished version of that cable on their website whereas ours is a rose-gold and black version which I actually prefer as it is a better aesthetical match to the bronze of the Allegro shells. If you do order perhaps ask PLUSSOUND if it is possible to have that combo if you like the look of it.
Packaging & Accessories
PLUSSOUND has upped its game a lot over the years when it comes to packaging. The Allegro presentation is not a grandiose affair like the Effect Audio Centurion cable from a few years ago but it is slick with more of a discreet executive styling.
The outer box is a classic PLUSSOUND low-profile compact box finished in black with a small graphic at the base indicating what the contents are. Inside, everything is neatly packaged away in a large leather case that PLUSSOUND sells separately for $99.
Opened up you either get a leather headphone stand that fits neatly inside the case or the stock felt display layer. The leather stand itself sells separately for $59 though sadly we do not have one here to discuss.
We do have the stock felt display tray which allows you to wrap the cable around a lower pillar and tuck the driver shells safely away at the top in their separate velvet pockets.
Of course, being an IEM product there are a few more things to include in the accessory line-up compared to cables alone. Underneath, you get a standard PLUSSOUND cleaning cloth and brush, a leather IEM organizer, and the 3 bags of aforementioned tips.
Sadly, no leather pouch comes with the Allegro lineup which normally comes with their cables. Granted you are getting a big sexy looking zipped brown leather case that looks better and probably costs a lot more to make. However, for pocket loves that little black leather case might have proved a more useful compact alternative.