In my previous post, we have discussed the importance of audio file formats. As a short refresher, the type of audio format you are listening to will affect the quality of sound your speakers are producing. Lossy compressed files such as .mp3 have a low fidelity representation of your music as it uses psychoacoustics algorithms to remove recorded components that are not important. High-end audio systems such as studio monitors or reference earphones will emphasise the flaws of these lossy compressed files and will obstruct the enjoyments to your listening experience.
Once you have invested in a library of high-quality songs that are to your liking, the next step would be a bit more interesting as we can finally talk about the hardware, specifically the interface. Onboard interfaces that are bundled with your media devices such as phones, laptops, and even mp3 players are usually not applicable for driving monitor speakers. This mainly boils down to two reasons, namely the quality of the digital to analog (DA) converters and the signal strength from the audio output (e.g. headphone output) in your devices.
DA converters that are inbuilt into your gadgets are typically below average in terms of data decoding capabilities, which affects the signal integrity of the files. The footprints of these converters are small, as they are designed to fit into a portable device, thus they do not have sophisticated DA circuitry to execute the task. Therefore, getting a DA converter, which has the specifications that are relevant to your playbacks files, would do just fine. To illustrate, if you are mainly listening to standard audio CDs (which are sampled at 44.1KHz, 16 bits) and do not see yourself spending more money into other formats (price can differ quite exponentially), a DA converter that supports 44.1KHz / 16 bits sampling rate will be acceptable for this scenario.
Due to my scope of work, I am currently using either the Avid Mbox Pro Generation 3 or the Dante Virtual Soundcard (with Dante supported devices) for my recording / mixing applications. As I do not solely listen to playback audio on my system, I would require some preamps input (audio input) for my recording purposes. These interfaces are specifically used for music production as they provide both an abundant of input and outputs buses for me to route and process the signals simultaneously.
There are many variations in interfacing your DA converters; the most common being connecting through a USB cable. Other options include FireWire, Thunderbolt and Ethernet connectivity. It is important to note that an audio amplifier is different from DA converters (though these features can be bundled together). While a converter decodes your digital files into analog signals, an amplifier will boost the signal strength. Therefore, buying an expensive audio amplifier while being connected to your onboard DA converters will not have any significant improvement in sonic fidelity.
On the other hand, there are very limited options in the market for portable devices such as mobile phones or mp3 players to provide alternative outputs other than the standard headphone output. As a result, many individuals choose to use a portable amplifier to increase the gain of the output, allowing the device to drive higher fidelity headphones (higher impedance). Do keep in mind that even though the signal is high enough to drive these power-hungry components, you are still using the onboard DA converters and the quality varies widely across products.
As for myself, if I am listening to music on the go, I will take the sonic characteristic (headphone / earphone) and convenience as my main consideration points. Hence, I would require my media devices to be as portable as possible while retaining the enjoyment in the listening experience. I do not use a portable audio amplifier on my iPod classic, as I disliked the introduction of the extra bulk and weight. Many years ago, I started using the AKG K450. This headphone is not only lightweight but does not require additional amplifications in order to drive the unit. Furthermore, I am fond of the K450's characteristic. Its sonic representation is impressive for such a compact footprint. Since then, my portable listening rig only includes an iPod classic and my traveling headphone.
DA converters are crucial components, as they will affect your overall audio system performance. They might not be as fancy looking as monitor speakers but they are often considered the backbone of your system rig.