Comparison M-AUDIO Bass Traveler vs xDuoo XQ-10

The nominal impedance (impedance) of the headphones for which the amplifier was originally designed.

Modern headphones can have different impedance. In particular, among the most popular options are 16 ohms and 32 ohms, and advanced models have values from 300 ohms and even from 600 ohms. High-resistance is considered to be "ears" with a resistance of 100 ohms. These characteristics improve the purity of the sound, but require increased signal strength — and built-in amplifiers in handheld devices, computer audio cards, etc. usually have difficulty with this. Therefore, external amplifiers are often used for this very purpose — to effectively "shake" high-end headphones with high impedance. For the same reason, some of these amplifiers are not compatible with low-impedance “ears”: there are many devices that require headphones with an impedance of at least 32 ohms, or even higher, and in some models the lower limit of the operating range can reach 100 ohms. As for the maximum resistance, the range of its values is very impressive — from 32 ohms in relatively simple portable "amps" to thousands and even tens of thousands of ohms in high-end stationary models.

Anyway, you should not violate the manufacturer's recommendations for headphone impedance. If the resistance of the “ears” is too low, at best, the sound will be s...ubject to noticeable distortion, at worst, equipment failure and even fire may occur. Too high resistance, in turn, not only reduces the volume, but also worsens the frequency response.

Rated power delivered by the amplifier when connected to headphones (or other load) with an impedance of 32 ohms.

By itself, the rated power is the highest average power that the device is capable of delivering for a long time without overloading; individual "jumps" of the signal may have a higher level, but in general, the capabilities of the amplifier are determined primarily by this indicator. At the same time, the physical features of the audio equipment are such that the actual power delivered to the load will depend on the resistance of this load. Therefore, in the characteristics of headphone amplifiers, data is often given for different impedance values. A resistance of 32 ohms allows you to achieve quite good sound quality by the standards of low-impedance headphones, while it is not so high as to create problems for the built-in amplifiers of smartphones and other compact equipment. Therefore, most wired general-purpose (non-professional) headphones are made precisely in this resistance, and if the amplifier characteristics generally indicate power for a certain impedance, then most often it is for 32 ohms.

In the most modest modern amplifiers, the output power at this impedance is between 10 and 250 mW ; values of 250 – 500 mW can be called average, 500 – 100 mW are above average, and the most powerful models are capable of delivering ...f="/list/788/pr-19429 /">more than 1000 watts. The choice for specific power indicators depends on the sensitivity of the headphones used, as well as on the sound pressure level (in other words, loudness), which is planned to be achieved by the amplifier. There are special formulas and tables that allow you to calculate the minimum required power for a certain volume at a given sensitivity of the "ears". However, in the case of 32-ohm headphones, it does not always make sense to "get into the calculations." For example, the mentioned 10 mW is more than enough to drive headphones with a modest sensitivity of 96 dB to a volume of more than 105 dB — this is already enough to listen to music at quite a decent volume. And in order to achieve the same "ears" level of 120 dB, which provides a full perception of the loudest sounds (like explosions, thunder, etc.), you need to give out a power slightly higher than 251 mW. So in fact, you have to pay attention to this characteristic and resort to calculations / tables mainly in those cases when you have to use 32 Ohm headphones with a relatively low sensitivity — 95 dB or less.

Rated power delivered by the amplifier when connected to headphones (or other load) with an impedance of 16 ohms.

By itself, the rated power is the highest average power that the device is capable of delivering for a long time without overloading; individual "jumps" of the signal may have a higher level, but in general, the capabilities of the amplifier are determined primarily by this indicator. At the same time, the physical features of the audio equipment are such that the actual power delivered to the load will depend on the resistance of this load. Therefore, in the characteristics of headphone amplifiers, data is often given for different impedance values. And 16 ohms is a rather low resistance indicator even for low-resistance "ears"; such characteristics are provided mainly in general-purpose headphones designed for pocket gadgets with low-power amplifiers.

As for the choice for specific power values, it depends on the sensitivity of the headphones used, as well as on the sound pressure level (in other words, loudness) that is planned to be achieved by the amplifier. There are special formulas and tables that allow you to calculate the minimum required power for a certain volume at a given sensitivity of the "ears". At the same time, it is worth noting that at 16 ohms, even the most low-power modern “amps” are capable of delivering about 20 mW — this is enough to drive headphones with a sensitivity of 88 dB (far from the highest figure) to a vo...lume of 105 dB (the minimum value recommended for a complete listening experience). And in most amplifiers, when operated with a given impedance, they provide much more power. So paying attention to this point and going into the calculations makes sense mainly either with low sensitivity of the "ears" (less than the mentioned 88 dB), or if you want to end up with a level above 105 dB.

Frequency range supported by the output amplifier; in other words, the range that this model is capable of delivering to headphones or another analogue audio device.

Theoretically, the wider the frequency range — the richer the sound of the amplifier, the lower the likelihood that the lower or upper edge of audible frequencies will be “cut off”. However, when evaluating this parameter, several nuances should be taken into account. Firstly, the average person is able to hear frequencies from 16 to 22,000 Hz, and with age, these boundaries gradually narrow. However, headphone amplifiers often have wider operating ranges, and they are very impressive — for example, for some models, a set of frequencies from 1 Hz to 60,000 Hz, or even up to 100,000 Hz, is claimed. Such characteristics are a kind of "side effect" from the use of high-end sound processing circuits; from a practical point of view, these numbers do not make much sense, but they are an indicator of the high class of the amplifier and are often used for advertising purposes.

The second nuance is that any headphones also inevitably have their own frequency limitations — and these limitations can be more significant than in an amplifier. Therefore, when choosing, it's ok to take into account the characteristics of the headphones: for example, you should not specifically look for an amplifier with an upper frequency limit of the full 22 kHz, if in the headphones that you plan to use with it, th...is limit is only 20 kHz.

In conclusion, also note that an extensive frequency range in itself does not guarantee high sound quality — it largely depends on other factors (frequency response, distortion level, etc.).

The ratio between the overall level of the desired signal produced by the amplifier and the level of background noise resulting from the operation of electronic components.

It is impossible to completely avoid background noise, but it is possible to reduce it to the lowest possible level. The higher the signal-to-noise ratio, the clearer the sound produced by the device, the less noticeable its own interference from the amplifier. In the most modest amplifiers from this point of view, this indicator ranges from 70 to 95 dB — not an outstanding, but quite acceptable value even for Hi-Fi equipment. You can often find higher numbers — 95 – 100 dB, 100 – 110 dB and even more than 110 dB. This characteristic is of particular importance when the amplifier operates as a component of a multi-component audio system (for example, "vinyl player — phono stage — preamplifier — headphone amplifier." The fact is that in such systems the final noise of all components at the output is summed up, and for sound purity it is extremely it is desirable that these noises be minimal

Separately, it is worth emphasizing that a high signal-to-noise ratio in itself does not guarantee high sound quality in general.

The coefficient of harmonic distortion that occurs during the operation of the amplifier.

Any electronic circuits are inevitably subject to such distortions, and the quality and reliability of the sound at the output depends on their level. Accordingly, ideally, the harmonic coefficient should be as low as possible. So, as a general rule, a level of 0.09% and below (hundredths of a percent) is considered good, and a level of less than 0.01% (thousandths of a percent) is excellent. The exception is lamp devices: higher values \u200b\u200bare allowed in them (in tenths of a percent), however, this point in many cases is not a drawback, but a feature (for more details, see "Lamp").

It is also worth noting that a low harmonic coefficient is especially important when using the amplifier as part of multicomponent audio systems — for example, when listening to music from a vinyl player with an external phono stage. The fact is that in such systems the sum of distortions from all components affects the final sound — and it, again, should be as low as possible.

The presence in the amplifier of special features for connecting iPhone, iPad and other Apple gadgets.

Usually, a standard USB port (microUSB, USB-C) is used for such a connection — the same as for other portable (or even stationary) devices. However, models with this feature are additionally optimized for use with Apple products, and may also have special functions for working with such gadgets — for example, playback control via remote control on headphones connected to the amplifier. So if you are purchasing an amplifier for use with an Apple gadget, it makes sense to pay attention to models that directly declare compatibility with such gadgets.

The total number of headphone outputs provided in the design of the amplifier.

Most modern headphone amplifiers are designed for individual use, but there are exceptions — you can find models for sale with 2 outputs and even 3 or more. The general essence of this design is obvious: it allows you to connect several headphones at once and use the amplifier for several listeners at once.

However, not all connectors can be of the same type. Among those there are classic mini-Jack (3.5 mm) and Jack (6.35 mm), as well as less popular balanced 2.5 mm micro-Jack, XLR and 4.4 mm Pentaconn.

— mini-Jack (3.5 mm). The most popular plug format among modern wired headphones. It is found in models of all price categories; and even high-end solutions that can be used with a more advanced 6.35 mm Jack, most often do not have a built-in Jack format connector, but a 3.5 mm plug and a complete 6.35 mm adapter. On the other hand, the acoustic properties of the mini-Jack are somewhat inferior to the "big brother"; therefore, this headphone connection format is found mainly among portable models (see "Type"), although there are also stationary amplifiers with such outputs.

— 6.35 mm (Jack). Plug format designed mainly...for fairly advanced technology, mostly stationary. The large size of the connector somewhat complicates its use in compact devices; on the other hand, due to this feature, the connection quality, reliability and noise immunity are much higher than that of the smaller 3.5 mm mini-Jack. And you can connect headphones with a mini-Jack plug to a Jack-type jack using a simple adapter; often such an adapter is even supplied with “ears”. Thus, 6.35 mm type outputs are found in most stationary amplifiers (see "Type") and are found even in some portable models.

— XLR. This connector is mainly for professional use, having a characteristic round shape, contacts in the form of pins (“pins”), and often also a latch on the rim for additional reliability in connection. This connector is used for the so-called balanced connection of headphones, which has a positive effect on the purity of the sound and allows you to use even long wires without additional risk of distortion. On the other hand, in the case of headphones, the need for such a connection arises relatively rarely, and there are not many "ears" themselves with an XLR plug — mostly high-end professional models. So in amplifiers, outputs of this type are mainly used in stationary devices (see "Type") of a premium level. Most often, a four-pin connector is used as such an output, often without a latch and/or reduced sizes. In general, in audio equipment, such a connector is less common than a three-pin one (see "Outputs"), but specifically in headphones it is the standard option — especially since 4 pins allow you to output both stereo channels through one jack (whereas three-pin jacks work in the format "one channel per plug"). However, there are amplifiers where a pair of three-pin XLRs plays the role of a balanced headphone output. At the same time, such connectors can be physically combined with 6.35 mm Jack outputs — in other words, a 6.35 mm jack is built right into the centre of the XLR connector. This makes the design more compact, but does not allow the use of both types of connectors at the same time.

— Pentaconn 4.4. Connection implemented by a 5-pin connector with a diameter of 4.4 mm. This is a relatively new balanced connection standard developed by Sony. Most often used as a line output for digital-to-analogue converters and amplifiers. Additionally, this connector can be found in multimedia players and even console consoles. The main advantage of the Pentaconn 4.4 standard is the ability to output an audio signal to sufficiently powerful high-impedance headphones. This standard is an alternative for not very practical Jack and XLR connections.

The type of power used by the amplifier.

In modern models, you can find mains power, battery and USB port. At the same time, some devices may provide two options at once (or even all three at once) — this allows you to choose the most convenient way of feeding, depending on the situation. In addition, there are amplifiers with support for Power Bank mode — this feature is also indicated in this paragraph, although it is not a type of power supply, but an additional function of models with a built-in battery.

Here is a more detailed description of each option:

— From the network. Powered from a conventional 230 V socket. Such power is very convenient from a practical point of view: the operating time of the amplifier is unlimited (as long as there is voltage in the network), and the output power can be almost any. The main disadvantage of this option is the actual dependence on sockets; however, for stationary models (see "Type") this point is not critical, so most of these devices use mains power (and most often — as the only option). There are also portable amplifiers with the ability to connect to the network — in such cases it is provided as an additional option that allows you to save battery power if there are outlets nearby (and most often also charge the battery during such use).

— From t...he battery. Powered by its own built-in battery. Such a power supply complicates the design of the amplifier, increases its weight and cost, and the operating time on a charge is inevitably limited. On the other hand, the battery allows you to work regardless of the presence of outlets nearby. Therefore, this option is extremely popular among portable amplifiers (see "Type") — especially since it is easier to achieve high output power with a battery than with USB power (which is also suitable for such equipment). But stationary solutions with their own batteries are extremely rare — and in them, usually, the battery is a “fallback option” in addition to another type of power supply (and in some stationary amplifiers, the presence of a battery also depends on the modification).

— From the USB port. Powered by a USB connector — usually the same one that is used as a source of digital audio signal. The features of such a power supply no longer depend so much on the specific amplifier, but on the device with which it is used. So, when used with a PC, such a connection is in many ways similar to connecting to a network: the operating time is unlimited, and the power of the amplifier can be quite high (although not as high as when using an outlet), but there is no talk of freedom of movement. Smartphones and other mobile gadgets, on the contrary, are autonomous, but their power outputs are not very powerful. On the other hand, it is most often not required for them, and the unequivocal disadvantage can only be called the moment that the amplifier additionally consumes the battery of the gadget. Connecting to a laptop combines the features of both options described above: the power supply is comparable to the USB ports of stationary PCs, while the laptop can work without an outlet.

— Power bank function. The ability to operate the amplifier in power bank mode — that is, an external battery for charging various gadgets, such as smartphones or pocket players. This function by definition means that the amplifier has a built-in battery (see above); the device itself is most often portable (see "Type"), however, there are also stationary solutions with Power Bank mode. Note that the specific battery capacity in amplifiers with this function is different; often it is very low, and the device allows you to “prolong the life” of the gadget rather than fully charge it. However, even this possibility can be very useful — for example, if you need to wait for an important call, but you forgot to charge your smartphone, and there is no charger or outlet for it at hand.