The ALO Rx comes equipped with a lot of tech packed into a slim box roughly the size of an Ipod Classic. ALO not only jumped on the digital/attenuator volume control wave, but they also added many other goodies to the Rx amplifier. It has dual Lithium Ion batteries, a battery monitoring charging circuit, and a digitally controlled dual stepped attenuator circuit. ALO claimed that the batteries last for 17-30 hours depending on volume, with only 2-4 hours of charging time.
All controls on the ALO Rx are conveniently placed on the front panel of the amplifier, including the charging terminal for the batteries. Volume adjustment is achieved through a spring-loaded toggle switch, similar to the RSA Shadow. Everything is nicely put together, though the build quality is just right.
I was immediately impressed with the wide soundstage presentation of the ALO Rx. Most of the time I find that the soundstage from IEMs are not big enough, but with the ALO Rx, IEMs find the boost they need. As a matter of fact, I can nominate the ALO Rx for the portable amplifier with the biggest soundstage. The ALO Rx is directly comparable with the TTVJ Slim, though each have their own sonic signature. Where the TTVJ has a more intimate presentation, the ALO is more open and wide. The TTVJ focuses more on the midrange, but the ALO gives a livelier treble for a more dynamic sounding effect. Both amplifiers are pretty equal in power, though the TTVJ at the high gain setting can drive full size cans to louder levels.
Previously if you want to get a nice clean sound from a portable amplifier, you’d have to get something that’s fairly big like the Ray Samuels SR-71a or the iQube. Not to mention the high pricetag that comes with those amplifiers. Those days are no more. I find the ALO Rx to be a good subtitute to my favorite portable amplifier, the SR-71a. Although the SR71a still packs more power than the Rx, I find the Rx to have an edge in a slightly bigger soundstage and a cleaner sound. Actually the Rx’s sound signature reminds me of the Triad Audio LISA 3 amplifier. It has the same clean sound with great dynamics, though the LISA 3, with its dual 9V batteries trumps the Rx in power.
I thoroughly enjoy the ALO Rx with both the UM3X and the Shure SRH-840. The amplifier have quite a beautiful synergy with both cans. Soundstage gets widened and dynamics are also improved. Particularly with the UM3X, the ALO gave a livelier sound and bigger dynamics to the flat UM3X, as well as boosting the mediocre soundstage to more enjoyable levels. I also find the Rx awesome for classical music, though I’m not limiting it to just that genre.
Overall the ALO Rx is a very good portable amplifier, and for $345, really challenges a lot of the higher priced portables.