A big part of the ALO’s appeal involves its delicacy and finesse, qualities that came into play in major way when listening to Gordon Getty’s Overture “Plump Jack” Ancestor Suite as performed by Sir Neville Marriner and the Academy of St. Martin in the Fields [PentaTone SACD]. Though only a little over twelve minutes long, the “Plump Jack” Overture presents a thoroughgoing orchestral workout for any headphone or headphone amp. For this particular listening session, I used Shure’s new flagship SRH1840 headphone, a headphone that, while not particularly difficult to drive, is extremely revealing both of recordings and of headphone electronics (honestly, these Shure ‘phones could serve as the “poster child” for the benefits of extreme openness and transparency). I reveled in the way the ALO/Shure pair captured the pure, distinct timbres and sonic signatures of each orchestral section and of individual instruments within the section. In particular, the Shure’s perfectly captured the elusive, melancholy sound of the French horns, and the uniquely luminous, liquid tonality of the harp. On this track and with this amp and the Shure’s working together, you have the sense of living within a sonic cornucopia—experiencing a literal horn of plenty as you move from one moment of sonic richness to the next.
If there’s any catch, and there is one, it would be that Shure’s SRH1840 headphones tend to sound overly lightly balanced from about the middle of the mid-bass region on down (the SRH1840’s can go quite low, but not with as much authority as you might want). Happily, though, the ALO supplies an answer in the form of its distinctive Bass Boost control. On Getty’s “Plump Jack” Overture, I found it was child’s play to dial in some much-needed low-end reinforcement, yet without making the sound muddy or overwrought. I simply turned up the boost control until I found a point where the Shure’s began to exhibit appropriate weight and depth on low strings and, and stopped when I felt the sound had reached a “sweet spot” in terms of overall balance. Happily, the boost control is designed for subtlety, not for excess, so that it is pretty hard to get the settings wrong. Better still, the control lets you add bass reinforcement as needed, yet without undercutting the inherent clarity or lucidity of the ALO amp’s sound. Once again, the ALO gives you sonic gain without pain.
Consider this portable headphone amp if:
• You want an accomplished portable amplifier that is equally at home on the go or in your listening room and that can successfully drive just about any earphone or (non-electrostatic) headphone ever made.
• You like the idea of a truly subtle, variable bass boost control that can add just a touch of low frequency reinforcement for those earphones or headphones that need a bit more low-end weight and punch.
• You want an amp that will pair beautifully with Cypher Labs’ way cool AlgoRhythm Solo high-performance portable DAC. There is close collaboration between ALO Audio and Cypher Labs, as a result of which the Rx MK3-B and AlgoRhythm Solo feature identically sized and shaped chassis. Together, they make what is perhaps the ultimate portable playback system.
Look further if:
• You want to push the edges of the headphone sound-quality envelope, as only a true top-tier desktop amplifier will allow. But recognize that stepping up from Rx MK3-B to something audibly better will cost you portability plus a pile of greenbacks.
Ratings (relative to comparably priced portable headphone amps):
• Design and Features: 9.5
• Tonal Balance: 10
• Timbral Purity: 9.5
• Detail & Resolution: 9.5
• Imaging/Soundstaging: 9.5
• Dynamics: 10
• Value: 9.5 - 10
As earphones and headphones become more and more specialized, the performance envelopes demanded of headphone amplifiers becomes broader and more daunting by the minute. Impressively, the ALO Audio Rx MK3-B not only meets the demands of an exceptionally wide range of earphones and headphones, but also does so in portable format, with beautiful build quality, and at a fair price for what you get. Sound quality is on par with today’s better desktop amps and better than that of many we have heard.
If you could only choose one headphone amp to meet all your listening needs, this one belongs at or near the top your short list. It’s one of the two best portable headphone amplifiers now being produced.
ALO Audio Rx MK3-B Fully Balanced Portable Headphone Amp
Type: Compact, battery powered headphone amplifier with fully balanced circuitry from input to output.
Accessories: As noted under “FEATURES”, above.
Inputs: Two switch selectable stereo analog inputs (one single-ended input via 3.5mm min-jack, one fully balanced input via miniature, square 4-pin connector).
Outputs: Two headphone outputs (one single-ended output via 3.5mm mini-jack, one fully balanced output via miniature, square 4-pin connector).
Other controls: single three-position master gain switches with settings for “Low”, “Medium”, and “High” gain; combination on/off switch and volume control, bass boost control that incorporates a built-in “defeat” switch.
Frequency response: 5Hz – 80 kHz, ± 1dB
Power output, balanced mode:
• 640mW into 32 Ohms
• 630 mW into 50 Ohms
• 150 mW into 300 Ohms
• 80 mW into 600 Ohms
Power output, unbalanced (single-ended) mode:
• 320 mW into 32 Ohms
• 220 mW into 50 Ohms
• 40 mW into 300 Ohms
• 20 mW into 600 Ohms
Gain setting options:
• High Gain: 12dB
• Medium Gain: 3dB
• Low Gain: -3dB
Bass Boost Control Range (with maximum boost applied):
• <0.5 dB at frequencies above 360 Hz
• 0.5 dB @ 360 Hz
• 1 dB @ 260 Hz
• 2 dB @ 160 Hz
• 3 dB @ 80 Hz
• 3.5 dB at frequencies below 40 Hz
Battery: 4400mAh Lithium-Polymer
• Play time: 10 hours, balanced mode
• Play time: 14 hours, unbalanced (single-ended) mode
• Recharge time: 3 hours
Dimensions (H x W x D): 0.75” x 2.87” x 5.16” (includes dimensions of control switches, etc.)
Weight: Not specified.
Warranty: 30-day Money Back Guarantee