Review: Stoner Acoustics Ruby – The Miniature Amp

Ruby is dead silent and I like that a lot. I have several very sensitive custom Balanced Armature monitors (like the Earwerkz Legend R) that pick up the slightest bit of floor noise and hiss, and a lot of recent portable amplifiers, even those made for IEMs, still make noise. The Ruby however is dead silent and that deserves big thumbs up.

Bass has very good body but it’s not the tightest or fastest bass you’ve ever heard. Bass is not overpowering anything and it’s not bleeding in to the mids. Bass detail, layering and timbre aren’t the amp’s strongest points but at the same time it’s perfectly normal and bass sounds pretty good. You just don’t get the level of the higher end amps, that’s all.

Like the bass, the (lower) mids also have good body but what’s missing most in the mids is the timbre and depth. The mids feel more concentrated and this makes the sound stage of the Ruby feel smaller. The upper mids are a little more forward sounding and are a bit thinner (less body). Treble is very inoffensive. Soft but reasonably extended. That means it’s not too sparkling and real treble lovers will probably not be excited by the treble presentation.

Competition

While Ruby isn’t specifically made for use with IEMs I do kind of consider it to be an IEM amp. Sure it can handle easer to drive headphones (more below) but I still think most people will be using it with their IEMs. When I think of IEM amps, three models pop up in my mind: the ALO Rx, CypherLabs’ Picollo and Fiio’s E12A. At the same time Ruby makes me think of the E11K and E10k units from Fiio.

Fiio’s E10K is 75.99USD and has a pretty awesome dac built in. It also seems to drive full sized headphones in a better way. It does seem like you’re paying a bit of premium for the micro technology in the Ruby but in the end this amp still only is $99. Fiio’s E11K is only $59.99 but I do prefer the Ruby over that one, that’s an easy decision. Ruby has more detail and is more linear/neutral.

Ruby is quite far away from amps like the Rx and Picollo, these amps simply score better on all fronts but cost several times what Ruby is going for as well, so there’s no shame in that.

Ear- and Headphones

Like I just said, Ruby is especially good for driving IEMs and low impedance headphones like the HD25, Vmoda XS, T51P, L2 etc. It’s not really recommended for harder to drive dynamics like the 250Ohm and 300Ohm favs of mine, and it’s certainly not recommended with orthodynamics (no surprise there). On the other hand, I quite like how Ruby manages to “drive” the 300Ohm Sennheiser HD650, they sound surprisingly good with reasonable deep bass and “schwung”.

My favorite on-ear headphone still is the Beyerdynamic T51P: Ruby gives it some more body and timbre in the midrange. The T51P really scales up nicely when using an amplifier. The Ruby gives it good bass body, smooth detailed and musical mids and a more rolled off easy treble. A good balance overall. Philip’s Fidelio L2 is a great headphone with lots of detail and good technicalities. The one thing it misses to me is (bass) body and that’s exactly what the Ruby adds to it. A very nice combination and I really should listen to the L2 a lot more! The Fidelio X2 is like the L2 but has a warmer/darker tuning with added bass body. Because of this, the matching with the Ruby isn’t the best as it doesn’t add anything to the sound and it doesn’t elevate the X2 in the way I would like it.

The open Audeze EL-8 (review soon) straight out of a DAP doesn’t always sound its best and the Ruby here mostly just adds power. The EL-8 however doesn’t sound as good as when used with a better amplifier like the Trio and Duet, I wouldn’t recommend it even for these lighter to drive orthos.

The CypherLabs C6IEM isn’t known for its strong treble (to say the least) and the Ruby doesn’t really improve that area either. However when you’re in to big (slightly slower) bass and thick mids, and you don’t find treble all too exciting this combo might be perfect for you. RHA’s T10 IEM is a very good, I personally like it most with the reference and bass filter. Combined with Ruby it sounds best especially with the Reference filter as Ruby will give that extra weight in bass and miss without holding back the treble. The brand new RHA T20, also on the reference filter, is an even better and clearer sounding IEM. Ruby makes it sound powerful and with the extra bit of bass slam it sounds very good. The T10 has more bass where the T20 is the more balanced of both, T20 review will follow over the coming weeks.

The custom Vision Ears VE5’s strongest points are the upper mids and treble, vocally strong music is superb on this monitor. Ruby again adds a bit of bass and lower mid body to the mix and the end result is extremely satisfying, especially as the V5 has a very wide sound stage (Ruby’s isn’t the largest). Cosmic Ears’ newest CE5P is very easy to drive and has an excellent natural tuning. I actually found it better sounding straight out of the DAP, it seemed like Ruby was holding it back in a way. Custom Arts’ first Acryl monitor, the Ei3, has a fun bass tuning with good mids and it sounds very good directly out of the source. It doesn’t have the widest sound stage however but the Ei3 is just extremely enjoyable (and cheap). The Ei3 unfortunately doesn’t sound its best with the Ruby, just like the CE5P. It seems a bit of a hit and miss thing with balanced armatures.

Conclusion

I love the Ruby. No, you won’t get the very best in sound like you get from an Rx or Picollo but for its price and size it actually performs quite well. On top of that it’s gorgeous, simple and extremely portable. If you’re new to the hobby and you want to have a good return on investment the Ruby might be just the amp for you. Or if you’re looking for an easy to carry, cheap, cool looking and good performing IEM amp, then I would certainly recommend it as well. If you’re more looking for something to use on your desktop, I would recommend something like the Fiio E10K which has the DAC built in. On the other hand when you combine one of Stoner’s DACs with the Ruby, you get an extremely small and portable setup with great sound for a great price.

Stoner Acoustics always manages to get good quality out of a tiny device at a sharp price. I’m very anxious to listen to their new EGA and EGD, I have a feeling those two have the potential to shake up the market, like NWAVGUY’s O2 once did.