这是一篇来自于ASR（Audio Science Review，音频科学评测）的评测。ASR是由前微软数字媒体副总裁Amir Majidimehr创办的一个音频设备客观主观评测的平台，具有很浓厚的工程师文化背景。

本篇文章由ASR的站长Amirm（前文提到Amir Majidimehr的站内ID）撰写。这篇文章从音频测量指标分析了双木三林 SP400 THX旗舰耳放的优异表现，提供了一个客观可信的参考角度。查看原文链接，请点击文章底部左下角的“阅读原文”。

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This is a review and detailed measurements of the SMSL SP400 balanced THX headphone amplifier. It was kindly sent to me by one of their dealers, shenzhenaudio. It costs US $630 from them.

这是关于SP400全平衡THX耳放的测评与详细的技术测量。是由双木三林其中一个经销商，SHENZHENAUDIO送测。大约是630美金的售价。（四千人民币左右）

The SP400 makes an attempt at luxury with glossy plexiglass top and digital display:

SP400使用了高级质感的玻璃顶板与全彩色显示屏。

As you see, there are no controls on SP400. Everything is menu driven including input selection and gain. If you use multiple headphones with different gain requirements, having to switch that using the menu can be a bit of a hassle. Fortunately there is a mitigating factor as you will see in the measurements.

如你所见，SP400上没有简单的物理开关控制。所有控制都是由菜单来进行，包括输入选择与增益。如果你使用多个耳机，需要不同的增益，你得使用菜单来进行控制。

One main distinguishing feature is that there is remote control and relay based R2R implementation. This should assure very good channel balance -- something that we will check later. It costs a lot to implement this feature though and that is reflected in the cost.

让SP400脱颖而出的功能，是遥控功能与步进的电阻音量控制。这种音量控制方式保证了优秀的声道平衡-我们会在之后确认。这种方式花费很高，当然也在SP400的价格上显现出来。

Forgot the picture of the back:

这是机器背后的接口图片

SMSL SP400 Measurements

SMSL SP400 指标测量

As usual with balanced input amps, let's feed the SP400 4 volts over its XLR input and ask for the same output over 1/4 HP jack:

照例，既然这是台有XLR平衡输入的放大器，我们使用4V的XLR输入并使用平衡耳机口4V的输出。

Distortion is stunningly low at nearly -140 dB so noise dominates our SINAD to the tune of 120:

失真极其低，低至约-140 dB，并且信纳比（SINAD）因此也低至120.

Please don't sweat one or two dB in this graph. That said, signal to noise ratio for low 50 mv output is a bit lower than it should be:

请不要太在意表中一两分贝的差距。这表示，信噪比在低至50mv的输出下，是比它应该的水平还低一些的。

Frequency response is of course rule flat to beyond 100 kHz:

频率响应很自然地很平直地超过了100kHz。

Measuring power into 300 ohm load shows that the different gain settings have almost no performance difference other than available amount of power:

在300欧姆的负载下，即使不同的增益，表现上也几乎没有区别。

Some other amps that get the best signal to noise ratio (and SINAD) tend to have a low gain mode with better performance. Here, the three modes are almost the same so I would just use the highest gain setting and be done with it. It is not like it impacts the channel balance as you will see later.

有一些其他的放大器，在低增益下会有更好的表现。这里，SP400的三档增益表现都几乎一致，所以我只用高增益并在此进行测试。增益选项不会影响声道平衡，你将会在之后看到。

Note that the first generation Massdrop THX 789 is bested in noise department.

我们注意到，第一代的Massdrop THX 789在噪声表现上，被SP400超越了。

Using balanced headphone jack we naturally get more power:

使用平衡耳机口，我们自然地有更多的功率驱动。

You have nearly 700 milliwatts which power just about any high impedance headphone.

SP400有接近700mW的功率，可以驱动任何的高阻抗耳机。

Switching to 32 ohm load we get similar picture:

换到32欧姆的负载，我们获得了类似的测量结果。

For consistency with previous tests, here is balanced not at 32 ohm but 50:
为了与之前的测试保持一致，这是50欧姆的测试结果。

We basically have a speaker amplifier with 4 watts of power with both channels driven.

从功率大体上看，这几乎是一个每通道4W的双声道放大器。

Using our latest test to check for load dependency we get:

使用最新的测试方法，来测量负载，我们获得了如下的结果

As you see, the amp does not care if the load is changed. It is happy to even drive 12 ohm load. To get the power at any of the tested impedances, simply follow the formula power=voltage * voltage/impedance.

如图所示，SP400并不在意负载的变化。在12欧姆的负载下表现仍然优异。在任何测试的阻抗下，获得的功率，简单而言依照简单的方程 功率=电压 x 电压/阻抗

Switching to balanced mode we of course get more power and some small signs of strain appear:

切换到平衡模式下，我们获得了更大的功率。

Max output is now at 14.4 volts but gets reduced below 32 ohm. At 6 volts there is finally some clipping.

最大的输出现在是14.4v，但在32欧姆下逐渐减少。在6v下有一些缩小。

Note that because there is no clipping elsewhere, the SP400 is "gain limited" meaning it could have been pushed harder. But decision was made to give you absolutely clean and transparent power to max volume

需要注意的是，因为除此之外没有其他的减少，SP400的“增益限制”意味着它本应该可以有更极限的表现。但最终他们的做法，是给你绝对干净与通透的功率，在最高音量下。

Finally here, is our channel balance demonstrating the value of the R2R volume control:

最终结果如下，优秀的声道平衡，让步进式电阻音量控制的好处充分展现。

SMSL SP400 Listening Tests

SMSL SP400 听觉测试

As usual I started my testing with Drop Ether CX low impedance headphone. The SP400 was cruising, driving this headphone with ease to incredibly high levels, causing neuron displacement in one's brain if you are not careful! There was no hint of distortion and extremely clean bass to treble response. Switching to Sennheiser HD650 had similar results with exceptional fidelity.

惯例，我使用Drop Ether CX这副低阻抗耳机开始i测试。SP400毫不费力地将这副耳机发挥地淋漓尽致，刷新听觉级的好！一点失真的迹象都没有，极度清晰的低音到高音。切换到森海塞尔德HD650，一样地好，极其保真。

I did hit a usability issue though that is common with R2R volume controls: they are slow to respond. You have to crank and crank the volume control to go from loud to average level. Wish they would add some kind of acceleration to the volume control and jump a bunch of steps when you rotate it fast.

我的确遇到了步进电阻音量控制常见的特性，调整音量的响应会慢一些。你得不停地调高音量，才能从高到平均的音量。希望双木三林能加入类似音量加速调节功能，让音量调节更迅速，当你转动地很快地时候。

Conclusions

结论

We another state-of-the-art headphone amplifier in the form of SP-400 with some differentiation in the form of R2R volume control which also gives you volume control should you want to use it as pre-amp in far-field listening. More choices in instrument grade headphone amplifiers with superb fidelity and seemingly infinite power availability.

又一个忠于音源与表达的耳放出现了！SP400加入了高精度电阻电路音量调节，同时也给你作为前级使用的功能，特别是当进行远场聆听的时候。SP400是市面上目前“仪器级别”的耳放，具有超高的保真度，与充沛的功率。

I am happy to put the SMSL SP400 on my recommended list.

我很高兴将SMSL双木三林SP400耳放列入我的推荐名单！