•Single-ended and balanced stereo outputs (implemented, respectively, via a 3.5mm mini-jack and the aforementioned miniature 4-pin balanced connectors). Whenever the amplifier is powered up, both the single-ended and balanced outputs are live.
•Switch-selectable master gain switches, with settings for low, medium, and high gain.
This feature lets users adjust the overall gain of the amp to match the sensitivity of their earphones and headphones. For instance, you might use the “Low” gain setting with high-sensitivity custom-fit in-ear monitors, the “High” gain setting with hard-to-drive full-size headphones, and the “Medium” setting for ‘phones falling somewhere in between.
The gain switch also effectively serves as a means of controlling the amplifier’s noise floor (choosing the “Low” gain setting gives you a lower noise floor but also reduces maximum available gain, while choosing the “Medium” or “High” gains settings will give you more available gain, but with an attendant increase in noise).
•Four-color indicator light:
Blue = play
Green = charging
Yellow = low battery
Red = very low battery/charge now
•Bass boost control: The Rx MK3-B provides a distinctive, variable-level bass boost control that can be defeated by rotating the control knob fully counter-clockwise. By design, the effects of the boost control are subtle, for the most part applying low-frequency boost below 80Hz with maximum impact down below 40Hz. Used in moderation, the control helps provide a touch of low frequency foundation at the bottom end of the audio spectrum, while maximum boost setting also add audible mid-bass and upper-bass enhancement.
•4400 mAh Lithium-Polymer battery pack that provides up to 10 hours of balanced mode playing time or up to 14 hours of unbalanced mode playing time. Charge time: 3 hours.
•Accessories include a wall-wart-type 9V battery charger and three ALO-labeled rubber straps for attaching portable DACs or music players to the Rx MK3B.
•Available in satin black and matte silver finishes.
Background: In our listening tests, we evaluated the Rx MK3-B with a wide variety of ancillary components as outlined below.
•Apple iPod Classic loaded exclusively with lossless CD-resolution files, with signals fed via high-quality line out dock (LOD) cable.
•Apple iPod Classic loaded exclusively with lossless CD-resolution files, with digital signal fed from the iPod to a Cypher Labs AlgoRhythm Solo portable DAC, with digital signals fed to the AlgoRhythm Solo and analog signals fed, respectively, through high-quality digital and analog cables from ALO Audio.
•Oppo BDP-95 universal/Blu-ray player, using the player’s balanced outputs with signals fed via high-quality balanced analog cables from Moon Audio.