The Device
The Simpl A1 amplifier is a small and light device that piggybacks to a full size iPod. It is made of white plastic with a high gloss finish and it matches the aesthetics of the iPod nicely. The manufacturer says the dimensions are 2.6"W x 3.3"H x .7"D, no weight is given but it's very light. Battery life is said to be 16 hours with a 2 hour recharge and I did not test battery life. To recharge the internal lithium-ion battery, attach the unit to a USB port on a computer with the supplied USB full size-to-mini cable.

The amp connects to the iPod's headphone out port via a short mini-to-mini interconnect cable that is included in the package. There is a power push button on the top with an LED that glows green when the unit is on, and on the side there is a mini USB connection with an LED to indicate charging status.

The Simpl A1 attaches via "podGrip" technology, as the company calls it. That amounts to some small rubber-like pads on the back and sides of the amp. The amp is shaped so it hugs the sides of the iPod. I found that the attachment system worked very well. It is surprising how securely it attaches to the iPod, but I couldn't shake it off. It never scratched the iPod either. To attach to the iPod, you simply push it on to the back, although spreading the wings of the amp helps to press it all the way on. To remove it, just insert a fingertip under one of the amp's wings and lift it away from the iPod and it comes right off. It is a nice system and helps to retain a lot of the portability of the iPod and adds very little weight or clumsiness to it. The only drawback, and this is to be expected, is that you can't use a case with the Simpl/iPod combination. Perhaps you could use a thin iPod skin, but I didn't try it.

The Sound
I tested the Simpl with 3 different headphones models, my home stereo, and in my car. With each test, I compared the sound of the Simpl output with the sound directly out of the iPod, using either or both of the iPod's headphone output or line out. As to be expected, my findings vary with the devices connected to the Simpl, but overall, I was disappointed with the sound quality.

Simpl With Headphones
Using the Simpl with the Grado SR60 headphones was perhaps the biggest disappointment. The Grados are detailed and warm sounding and they have a great soundstage. They are also fairly easy to drive and the iPod does of respectable job of it unassisted. With the Simpl, the Grados sounded dull and one-dimensional. The details were smudged, the highs were dulled, the bass sounded slightly overdriven, and the soundstage became flat. What's more, a hissing noise floor was distracting.

The Etymotic ER-6i canal phones were next. Again, the noise floor was so prominent as to be heard in soft passages of the music. Because the Etymotic ER-6i are so easy to drive and so efficient, you could listen to a few of the louder music tracks WITH THE VOLUME OF THE IPOD OFF! That is a testament to the Simpl, that it is in fact boosting the volume by quite a bit. However, be careful with this amp and canal phones especially - it is easy to accidentally play it too loud. With these phones, the highs were rolled off just a little bit, but the low end sounded richer and fuller. This was actually complimentary to the sound and made the Etys more musical. However, the sound suffered from a loss of detail, and combined with the prominent noise floor, I still preferred the sound of the iPod unamped.

Using the Simpl to drive the Shure E3c canal phones I heard the prominent noise floor again. The Simpl improved the volume and extension of the bass frequencies and made the Shures have a very good bottom end. However, it seemed to blur the sound and details and it foreshortened the soundstage. Mixed bag.

These three headphone models are all low impedance types that are relatively easy for an amplifier to drive. They are also common and popular headphones models for iPod listeners. Having said that, the Simpl may be more suitable, and might do a better job of driving high impedance headphones that need the extra horsepower provided by a headphone amp. When I contacted them about it, Simpl did recommend that I try high impedance headphones. However, the written material that Simpl provided me states that it will make all headphones sound better and it does not specify a recommended impedance range like some headphones amps from other manufacturers do.

Simpl With Home Stereo
I listened to the iPod via the Simpl, the headphone out, and line out. Using the Simpl on my home stereo, the prominent noise floor that was so audible with the headphones was much quieter and was within acceptable tolerances. But again, the sound stage was not as involving and the details were smudged. Even the headphone out connection sounded better to my ears.

Simpl In The Car
I've had a difficult time getting decent sound from the iPod in the car. Partly due to the complexity of my car's sound system (3 amps, 7 speakers) and partly due to the sound it makes - a detailed and prominent high-end matched with a powerful, extended low end - revealed too much of the limitations of the iPod connection. I don't have aux in capabilities in the car so the FM modulator has been the best connection method that I've tried, but it still suffers from a low volume and exaggerated bass. I had hopes that using the Simpl in the car might improve things and level out the frequency spectrum, but it made no change in the sound quality at all. This tells me that the weak link in the chain is the FM modulator, and this should not be a reflection on the Simpl. I only mention this to illustrate that I attempted to test the Simpl in many different environments.

Add It Up
Note that the Simpl does not have a volume control. If it did, you would have the additional option of connecting it to the iPod via line-out signal, which would most likely improve sound quality. A volume control is standard on other headphone amps, and a line out signal is really the best way to go for sound quality so it is a shame that the Simpl cannot be connected to the iPod in this manner.

The Simpl is a great design that suffers from flawed sound quality. It's such a shame too, because it's light, attaches to the iPod well, has decent battery life, and it's attractive. The literature Simpl provides claims that it works with any headphones and that has not been my experience. If you have special needs, or perhaps some high impedance headphones you might give it a try. 2/5 stars.

Website: Simpl

The good: Attractive design, good battery life, light, "podGrip" mounting system works very well.

The not so good: sonic flaws too serious to make this amp enjoyable to listen to.

Associated Equipment
Home System: Simpl, iPod headphone out, or line out via Sik din > Audioquest mini-to-RCA converter > MIT Terminator 3 interconnects > Proton AM300 > Tara Labs Omni speaker cable (biwired) > Energy C-2 loudspeakers > sand-filled/spiked steel speaker stands, Salamander equipment rack, custom aluminum billet spikes for amp.