The first ALO Audio RX amplifier came out in 2009. Now the company has improved it, specifically for in-ear monitors (IEMs) and earphones. So what is so special about this new little amp? Does it truly enhance the listening experience of IEMs? Today, I’ll try to find out with this ALO Audio RX IEM amplifier review.

In the Box – ALO Audio RX IEM Amplifier Review

-ALO RX Earphone Amplifier

-Micro USB to USB Charging cable and power supply

-Carrying case

-Three straps

Specifications – ALO Audio RX IEM Amplifier Review

-Frequency response (measured at 1 V RMS Output): 20 Hz to 20 kHz @ +/- 0.05 dB; 20 Hz to 50 kHz @ +/- .6 dB

-THD+N, (measured at 1 V RMS output): less than .002% from 100 Hz to 50 kHz

-Input Impedance: 10k ohms

-Output impedance: less than .5 ohms

-IEM optimized variation: Output power is limited by design to a safe power level of 20 mW

-Gain: approximately -14.6 db

-Battery life: 24 hours

-Charging time: about 3 hours

Design – ALO Audio RX IEM Amplifier Review

Looks, Portability, and Durability

The ALO Audio RX, which is about the size of a deck of cards, has a minimalistic design. It is monochromatic, and its only bits of flare are the air vents along the sides of the housing. Simplicity seems to have been a priority with this design, and it comes as a relief from the sea of extravagences in the many other products coming out these days. It’s metal housing seems super durable, however it is also spectacularly light. As a result, the ALO Audio RX is super portable and durable. However, the vents on the sides might be the one site of weakness where dust and dirt can get it, so treat it well, folks. Don’t go on a walk through a dust storm with this amplifier.

Technology

Dynamic Range

As with so many of the best amplifiers out there, it seems a lot of attention was paid to the power filtering of the ALO Audio RX. As a result, it has a wonderfully low noise floor. Additionally, it has a 15 V power supply which expands its headroom. As a result of the combination of these two facts, its dynamic range is dynamite. This is evident in its sonic performance and how it reproduces sound at various listening levels. More on this in the “Sound” section of the review.

Distortion and Coloration

There are two main features that work to decrease distortion and coloration. One is the ALO Audio RX’s low impedance output. This low impedance output differentiates it from other amplifiers out there because it controls the output so that it enhances the power supplied to low impedance earphones in particular. Additionally, this low impedance output affects the damping ratio. The damping ratio refers to the control of the diaphragm of the in-ears. As a result, the RX prevents the diaphragm from bouncing (which would produce ring and unpleasant coloration or distortion).

Next, the other feature at work to minimize distortion and coloration is the cut-off frequency of the amp. The cut-off frequency naturally creates some distortion and coloration near it in the frequency spectrum. ALO set the cut-off frequency at 80 kHz so all the colorationa and distortion would happen well above the human range of hearing. Therefore, the RX is able to reproduce signals totally clear up through 50 kHz.

Charging and Battery

The battery life of the ALO Audio RX lasts for about 24 hours. It takes approximately 3 hours to fully charge. You can charge the amplifier with any USB charging setup because the amplifier will change its charging current based on what the charger is supplying.

Sound – ALO Audio RX IEM Amplifier Review

In order to judge the sound, I listened to a pair of IEMs through both my phone and the ALO Audio RX. I switched back and forth between the two, shuffling between all different genres of music. This is what I found:

Soundstage

Listening through the ALO RX, the instruments in my music, in a general sense, were more clearly and precisely place in the soundstage. It was easier to place instruments at an exact spatial position. For example, in one mix (which consisted of drums, bass, horns, and two guitars), the reverby horns and the guitars would blend together so that I couldn’t quite tell which was which when listening straight from my phone. However, when I listened via the ALO Audio RX, I could hear exactly where the guitars and horns began and stopped in the left to right spectrum.

Additionally, listening via the ALO Audio RX, cymbals, reverbs, and other sustained decays in my music (like a staccato piano or string hit) sounded longer, more intricate, and more realistic. This seemed to improve my music’s perceived sense of depth as well.

Musicality

Listening to bright female vocals through both my phone and the ALO Audio RX surprised me. The RX sounded warmer than my phone and actually eliminated unpleasant sibilance. Additionally, the low end sounded tighter than on my phone. As a result, kick drums, toms, bass guitars, and other low end instruments sounded punchier and clearer than they did on my phone.

I wasn’t expecting so much added musicality out of this little device, but alas, it very clearly outperformed the level of emotional impact given by just using my phone.

Overview – ALO Audio RX IEM Amplifier Review

The ALO Audio RX is a simple, yet unique device to add to an IEM-loving audiophile’s on-the-go setup. Pairing it with your favorite IEM will enhance your listening experience in a way you won’t quite be able to reach with any other amplifier because other amps are not designed with IEMs in mind.

The ALO Audio RX is available for purchase right here at Audio 46.