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Old 10-11-2018, 11:20 AM   #13
wwenze
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Also, there is a reason why I weigh noise and crosstalk much more heavily than distortion for my verdict.

Well, firstly we have to understand the diminishing returns. Beyond a certain level of performance, we can't hear it anyway. But this also means poorer than a certain level of performance, we can hear it and what we hear gets worse if the performance gets worse. So the starting few dB of performance is more important than the last few dB, and it is more important to have an all-rounded performance than excellent in one but poor in another.
How low humans can hear versus the main signal is always being debated. There are estimates of -40dB (or 1%) to -60dB (or 0.1%).

And more importantly, when you reduce the volume:

- Noise gets worse
- Distortion gets better
- Crosstalk stays around the same (can be better can be worse)
- THD+N gets worse

And distortion getting better is mostly due to the distortion becoming lower than the noise floor. I mean, say the distortion is -80dB (0.01%) but your signal is only 70dB above the noise floor. The distortion is smaller and buried by the noise. But THD+N gets worse because of the N.

And because we don't always listen at high voltages, we are going to be using lower voltages where noise is going to be the bottleneck and distortion is too low to be heard. This is especially true for IEM and pretty much anything with high sensitivity in terms of dB/V.

And so the below is the comparison of Honor 8 Pro 3.5mm and SXFi at my usual listening level, with a Klipsch x11 connected (Rated impedance 50 ohm):


Crosstalk:
3.5mm: -49.9dB
SXFi: -47.1dB

The 3.5mm does have higher distortion. However that peak at 3kHz is still more than 60dB away from the signal. On the other hand, the SXFi has worse THD+N numbers. Because the RMS of the noise is greater.

The same trend continues even at higher output volume. Below is the max volume of Honor 8 Pro 3.5mm, with the SXFi compared at the same volume. Noise is still the main reducer of performance.



Which means, unless you need the higher output voltage of SXFi,

The SXFi does not give better amp performance than a smartphone, at least with lower impedance headphones.

Except one thing I almost forgot: Output impedance of Honor 8 Pro is ~3.9 ohm. Most phones tend to not have low output impedance so that is one advantage the SXFi AMP retains.
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Last edited by wwenze; 10-11-2018 at 11:45 AM..
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