Earphones and Custom-Fit In-Ear Monitors:
•Audeo by Phonak PFE 232
•Westone Elite Series ES5
•Ultimate Ears In-Ear Reference Monitors and Personal Reference Monitors.
•HiFiMAN HE-400 and HE-6
The Sound: The ALO Rx MK3-B delivers overall sound quality that is fully comparable to that of an accomplished, full-size desktop amp. By this I mean that it shows all the hallmarks of larger amps: robust and well-controlled bass, authoritative and well-defined sound, and plenty of dynamic clout. What’s more, it also shows a thoroughly refined quality of smoothness so that even when reproducing small, low-level details it never exhibits the sharp, piercing, edginess that spoils the presentation of some transistor amps.
One area of particular strength is the entire bass region, where the ALO sounds taut and detailed, provides very fine low-frequency pitch definition, yet is also appropriately weighty, powerful, and punchy. Use the ALO to drive ‘phones with first-rate bass (e.g., the Audeze LCD-3 planar magnetic headphones) and you’ll find it easy to get lost in the sheer beauty and inner detail of low frequency instruments such as pipe organs, tympani, acoustic and electric basses, kick drums, etc.
Another welcome touch is the ALO’s Bass Boost control, which provides really subtle touches of low-end reinforcement without imposing a big, overblown, mid-bass sound the way some conventional “tone controls” do. The control can be a godsend for those who basically appreciate their current headphones, but yearn for a little more low-end weight. With the ALO, you can apply tasteful bass reinforcement at the twist of a control knob (or switch the bass boost circuit off altogether if that’s your preference).
Another key area of strength involves the Rx MK3-B’s midrange, which is highly transparent, well detailed, and highly dynamic, and yet consistently delivers that oh-so-elusive quality of refined smoothness I mentioned above. After listening to challenging orchestral passages first through the ALO and then through competing amps, I found the ALO was typically able to equal or, more likely, to surpass the performance of like-priced portable amplifiers in terms of the sheer amount of musical detail and nuance it could reproduce. When I tried this comparison between the Rx MK3-B and the also superb Ray Samuels SR-71B Blackbird, I found the outcomes were very close, that—to my ears—the ALO eked out a narrow but consistent performance edge over the SR-71B.