DAC
DAC model — a digital-to-analogue converter installed in the amplifier.
In accordance with the name, the DAC is responsible for converting a digital signal (for example, coming to the optical input or USB, see "Inputs") into an analogue format, with which the amplifier directly works. The presence of such a converter in an external "amplifier" is important, given the fact that many popular signal sources — such as smartphones or built-in sound cards — are equipped with fairly simple and inexpensive DACs with low sound quality; on external equipment, this quality can be much higher. And the quality of the conversion and, accordingly, the characteristics of the output sound directly depend on the characteristics of the DAC: even the most advanced power amplifier will not “save” a signal converted with significant errors. Accordingly, knowing the converter model, you can find detailed data on it — from official specifications to practical reviews — and evaluate how an amplifier with such a module meets your requirements.
Power (32 Ohm)
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.
Power (16 ohm)
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.
Signal to noise ratio
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.
Bluetooth
The presence of a Bluetooth module in the amplifier for direct wireless communication with other devices - primarily with audio sources that also support this technology (for example, a smartphone, tablet or laptop).
The main convenience of
Bluetooth amplifiers is, first of all, the absence of additional wires, which can create various inconveniences. At the same time, the range of wireless communication is usually at least several meters. On the other hand, during normal transmission via Bluetooth, the digital audio signal is heavily compressed, which worsens the sound quality. To correct the situation, Bluetooth models may include aptX technology, which increases the purity of the signal almost to the level of wired Audio CD (or even Hi-Res Audio - in the aptX HD version); however, such functionality significantly affects the cost, and sophisticated music lovers often easily notice the difference between aptX and a wired connection.
In light of all the above, Bluetooth does not make sense to install in stationary equipment, so nowadays such modules are used only in portable amplifiers (see "Type"). At the same time, some of these models are positioned not so much as amplifiers, but as Bluetooth adapters for wired headphones. Nevertheless, such a solution can be a good alternative to classic wireless headphones: decent wired "ears" in combination with a Bluetooth amplifier can provide higher sound quality at a comparable,
...or even lower cost, and often such a set turns out to be even more "long-playing" in terms of work without recharging.
