内容来源：https://www.engadget.com/2273783/amplifier-what-for-how-important-for-sound-system-quality/

内容总结：

功放究竟有何作用？它对音响系统音质有多重要？你可能家中早已隐藏着好几台。

音响厂商乐于向消费者推销各种配件以提升音质，市面上甚至还能买到镀金音频线，尽管它们对数字音频并无实质改善——数字信号要么干净，要么不干净，没有中间地带。在真正值得关注的产品中，功放占据重要位置，无论是搭建家庭影院还是打造私人音乐空间，当地精品音响店数十年来持续销售功放并非没有道理。

然而，购买新音箱时并不一定需要同时购置功放。关键在于理解功放的功能、它在实际中能提升多少音质，以及你是否真的需要单独购买一台。如果你刚接触“严肃”音响领域，可能会惊讶地发现，家中其实已经隐藏着好几台功放，这恰恰说明了这项技术的基础性重要性。

同时，有必要澄清一些常见误解，不仅包括是否需要独立功放，还涉及电子管功放天生优于晶体管功放等观念。不要仅仅因为某件设备摆在架子上好看就花数百美元购买。你的目标应该是获得高品质音频，而非向朋友炫耀——而且可能有更具性价比的系统升级方式。

功放如何提升音响系统

大多数音频信号本身并不足以被清晰听到。只需一台关闭音箱的唱机即可验证：仔细听，你会听到唱针在黑胶纹路中运行时发出的微弱“唱针声”，音量极低，甚至难以辨认为音乐。要让任何音响系统发出有意义的声音，都需要功放在输出前增强信号强度。功放与音箱的功率和阻抗规格（分别以瓦特和欧姆为单位）需匹配。

功放的作用不止于增大音量。任何优质功放都允许你通过均衡器调整增益（信号增强量）并按偏好塑造音色，例如增强低频或使人声更清晰。正确设置增益和均衡器不仅关乎听感，还能防止削波、失真甚至硬件损坏。

这里需要区分功放与前置放大器。前级仅将音频提升至线路电平，以确保整个系统中增益正确，因此你仍需要功放来驱动音箱。部分功放内置前级，可简化音频链路。

这就引出了一个问题：你是否真的需要购买功放？事实上，很多情况下并不需要。许多（甚至大多数）消费级音箱是有源音箱，即已内置功放，从各自的电源线即可看出。只有无源音箱需要外部电源，即便如此，也未必需要专用功放。接收器通常集成功放和前级功能，堪称一站式解决方案。功耗极高的系统可能额外需要功放，例如超出接收器可同时驱动声道数的复杂杜比全景声配置。

大多数人应选择晶体管功放而非电子管功放。电子管功放以“温暖”音色和复古外观著称，但每台通常输出不超过50瓦，不适合环绕声配置，除非你愿意购买多台。电子管还需更多维护，即磨损后需更换。试图用电子管功放搭建家庭影院将是昂贵而徒劳的尝试。

更具性价比的音质升级方式

很多时候，真正值得升级的是音箱品质。如果你只有基础立体声回音壁或一对音箱，升级到高功率一体化全景声回音壁将带来巨大差异。如果已具备这一条件，可以考虑增加后置和侧置声道以增强声音分离度。添加顶置声道是发烧友的终极目标，但安装和布线可能带来的麻烦远超其价值。

许多改善方式成本更低。不必要的共振可通过垫子或音箱支架解决；多余混响可用吸音板减少；浑浊的低音有时只需将音箱移离墙壁即可改善。如果你的智能音箱具备自动房间校准功能，每次大幅调整空间布局后都应运行该程序。

如前所述，功放在音响系统中确有一席之地。但如果你使用的是有源音箱或接收器，除非进入高端领域，否则功放很可能是多余的。换言之，如果你没有7.2.4声道家庭影院，也没有整面墙专门用来沉浸于平克·弗洛伊德和Dr. Dre的音乐，那你大可以省下这笔钱。

中文翻译：

放大器有什么用，它们对你的音响系统质量有多重要？你可能已经有好几个藏在眼皮底下了。

音响器材厂商会很乐意卖给你上百种不同的配件来提升你的音响系统。时至今日，你仍然可以买到镀金音频线，尽管它们并不能真正改善数字音频——你要么得到干净的数据信号，要么得不到。在真正值得认真对待的产品短名单上，放大器占有一席之地，无论你是在搭建家庭影院还是属于自己的私人音乐圣殿。你当地的精品音响店几十年来一直在卖这些东西，这是有原因的。

不过，你不应该在新买一套音箱时就自动配一台放大器。关键是理解放大器到底做什么、它在现实世界中能把音质提升多少，以及你到底需不需要单独买一台。如果你是“认真”玩音响的新手，你可能会惊讶地发现，你家里大概已经有好几台放大器，就藏在眼皮底下。这恰恰说明了这项技术的根本重要性。

在此过程中，也值得澄清一些常见的误解。这些误解不仅包括“是否需要单独购买放大器”，还包括诸如“电子管放大器天生优于晶体管放大器”之类的观念。不要因为某样东西摆在架子上可能好看，就忍不住花上几百美元。想必你的目标是获得高品质音频，而不只是向朋友炫耀——而且可能有更具性价比的方式来升级你的系统。

放大器如何改善你的音响系统

大多数音频信号本身并不足够强，无法被清晰地听到。想要验证这一点，你只需要一台关闭音箱的唱机。如果仔细听，你会听到一种叫“唱针发声”的声音——唱针沿着黑胶唱片纹路运行发出的声响。这个声音很轻，甚至可能听不出是音乐。要让你听到任何有意义的内容，所有音响系统都需要放大器，在输出之前增强信号强度。重要的是，要让放大器的功率和阻抗规格与音箱匹配，分别以瓦特和欧姆为单位。

放大器的作用不只是增大音量。任何有品质的放大器都能让你调节增益（信号放大的幅度），并通过均衡器（EQ）按你的偏好塑造声音。比如，你可以调整频率来获得更重的低频或更清晰的人声。正确设置增益和均衡器不仅是为了获得悦耳的声音，也是为了防止削波、失真，甚至硬件损坏。

让我们花点时间区分一下放大器和前置放大器。后者只是把音频提升到线路电平，以便在整个音响系统中获得正确的增益，这意味着你仍然需要一台放大器来驱动音箱。有些放大器内置了前置放大器，从而简化了音频链路。

这就引出了一个问题：你到底需不需要买放大器。事实是，在很多情况下，你并不需要。许多——甚至大多数——消费级音箱是有源音箱，也就是说它们已经内置了放大器，这一点从它们各自带有电源线就能看出来。只有无源音箱才需要外部电源，而即便如此，你也未必需要一台专用设备。接收器通常集成了放大器和前置放大器功能，堪称一站式解决方案。功耗特别高的系统可能还需要在此基础上再加一台放大器。例如，复杂的杜比全景声系统如果超出了接收器能够同时驱动的声道数量，就需要额外加一台放大器。

大多数人可能应该选择晶体管放大器，而不是电子管放大器。虽然电子管型号以提供“更温暖”的声音和视觉上的精致感而闻名——尤其对《辐射》那种复古未来主义风格的粉丝来说更是如此——但它们通常每台只能输出50瓦或更少，因此不适合环绕声配置，除非你愿意花大价钱买好几台。电子管还需要更多维护，也就是在老化时更换。试图用电子管放大器来搭建家庭影院，只会是一场昂贵而徒劳的尝试。

更具性价比的音质升级方式

更常见的情况是，真正值得升级的是你所拥有的音箱质量。如果你只有一套基础立体声条形音箱或一对音箱，升级到高功率的一体式全景声条形音箱会带来天壤之别。如果你已经有了后者，那么也许是时候增加后置和侧置声道，以增强声音分离度了。对发烧友来说，增加顶置声道是终极目标，但考虑到你既需要安装又需要布线，它们很可能得不偿失。

很多改进其实便宜得多。不必要的共振可以通过垫子或音箱支架之类的附加用品来解决。你可以用吸音板减少不需要的混响，而有时候浑浊的低频可以通过把音箱挪得离墙更远来修正。如果你的智能音箱带有自动房间校准功能，那么每当你对空间做出重大调整时，都应该运行一次校准。

正如我们所说，放大器在音响系统中确实有它的位置。只是如果你使用的是有源音箱或接收器，那么在你进入高端领域之前，它们很可能是多余的。换句话说，如果你没有一套7.2.4声道的家庭影院，也没有一整面墙专门用来躺着听平克·弗洛伊德和Dr. Dre，那你大概可以把钱包收起来了。

英文来源：

What are amplifiers for and how important are they to your sound system's quality?
You probably already have a few hiding in plain sight.
Gear makers will gladly sell you a hundred different add-ons to improve your sound system. To this day, it's possible to buy gold-plated audio cables, even though they can't really improve digital audio — you're either getting a clean data signal or you're not. On the short list of products to take seriously is an amplifier, whether you're building a home theater or your own private music sanctuary. There's a reason your local boutique audio store has been selling them for decades.
You shouldn't automatically pick up an amplifier alongside a new set of speakers, however. It's critical to understand what an amplifier does, how much it can improve sound quality in the real world and whether you need to buy a separate one at all. If you're a newcomer to "serious" audio, you might be surprised to learn that you probably have several amps in your home, hidden in plain sight. That speaks to the underlying importance of the technology.
It's also worth tackling some fundamental misconceptions along the way. Those include not just the necessity of separate amps, but notions like the inherent superiority of tube amps to solid-state models. Don't buy into the temptation to spend hundreds of dollars on something just because it might look good on your shelf. Presumably, your goal is high-quality audio, rather than just showing off to your friends — and there may be more cost-effective ways to upgrade your system.
How amplifiers can improve your sound system
On their own, most audio signals aren't strong enough to be heard clearly. For a demonstration of this, all you need is a turntable with its speakers disabled. If you listen closely, you'll hear something called "needle talk" — the stylus running along the vinyl grooves. This is quiet, and it may not even be distinguishable as music. For you to hear anything meaningful, all sound systems need an amplifier to increase the strength of a signal before output. It's important to match an amp to the power and impedance specs of your speakers, measured in watts and ohms, respectively.
Amps accomplish more than just an increase in volume. Any quality amp will let you adjust gain (the amount of signal boost) and shape sound to your preferences via its equalizer (EQ). You might tweak frequencies for heavier bass or clearer vocals, for example. It's important to get gain and EQ settings right not just for pleasing sound, but to prevent clipping, distortion or even hardware damage.
Let's take a moment to distinguish between amps and preamps. The latter simply raise audio up to line level for correct gain throughout your sound system, meaning that you still need an amp to power your speakers. Some amps have a preamp built-in, streamlining the audio chain.
That leads us to the question of whether you need to buy an amp at all. The truth is that in many cases, you don't. Many, if not most, consumer speakers are active, meaning that they already have integrated amps, as evidenced by their individual power cords. Only passive speakers require external power sources, and even then, you may not need a dedicated unit. Receivers often incorporate both amp and preamp functions, making them a one-stop shop. Exceptionally power-hungry systems may demand an amp on top of that. For example, elaborate Dolby Atmos setups that exceed the number of channels your receiver can power simultaneously will need an amp.
Most people should probably opt for a solid-state amp rather than a tube-based one. While tube models famously provide a "warmer" sound and are visually slick — especially for fans of Fallout's brand of retrofuturism — they typically deliver 50W or less apiece, making them unsuited to surround-sound configurations unless you're willing to spring for several of them. Tubes also require more maintenance, namely swapping them as they wear out. Trying to run a home theater based on tube amps would be an expensive exercise in futility.
More cost-effective sound upgrades
More often, it's the quality of the speakers you have that could stand to be upgraded. If you've got a basic stereo soundbar or speaker pair, jumping to a high-powered, all-in-one Atmos bar will make a world of difference. If you've already got that, it might be time to add rear and side channels for enhanced sound separation. Adding ceiling channels is the endgame for an audiophile, yet they can potentially be more trouble than they're worth, given that you need to both mount and wire them.
A lot of improvements are far cheaper. Unwanted rattling can be solved by add-ons like mats or speaker stands. You can reduce unwanted reverb with acoustic panels, and sometimes muddy bass can be fixed by moving speakers farther away from your walls. If you've got smart speakers with automatic room calibration, you should be running that process whenever you make significant space alterations.
As we've said, amps do have a place in sound systems. It's just that if you have active speakers or a receiver, they're probably redundant until you reach high-end territory. In other words, if you don't have a 7.2.4-channel home theater, or an entire wall devoted to kicking back with Pink Floyd and Dr. Dre, you can probably tuck your wallet away.