SMSL SP400 Review (headphone amp)

[bgtip]

...
Especially considering I don't think the volume is linear. 79-89 seems like it's a much bigger jump than 29-39 on the volume knob, but I'll have to measure this with multimeter sometime to be sure.

Yes, it's interesting to see how linear the volume is. I think SMSL claimed it's linear, or nearly linear, and that is the reason to feel like less power. They claimed they did this on purpose to improve the 'useful' range.

 

[cursive]

Higher end of the scale? What do you listen to?
This is my moderate listening level on 99dB sensitivity Goldplanar GL2000:

View attachment 114549

I meant higher end of the scale in response to Chuck powering his Susvara which is a really inefficient headphone.

Me personally, my most demanding headphone is hifiman HE 560 @90dB sensitivity, and Im usually at 50-60 max on the volume with those.

 

[cursive]

Yes, it's interesting to see how linear the volume is. I think SMSL claimed it's linear, or nearly linear, and that is the reason to feel like less power. They claimed they did this on purpose to improve the 'useful' range.

Hmmm you're right there is some interesting wording on their site regarding the volume. Makes me wonder if you're truly only using 99 of the 256 steps on the relay, and if so, why use a 256 step relay system if they can't be used?

We just need a software engineer to hack the software and unlock 256 volume steps, and extra gain haha.

 

[Chuck S]

That’s the difference between 83 and 99 dB sensitivity.

To quantify what I was complaining about, my Cayin iHA 6 is rated at 5-7 watts per channel depending on current output. With the Cayin at 50% volume, the Element X volume was usually at -20 dB.

On the other hand, to get reasonable volume at -20 bB required 95% on the SMSL.

Big difference. I hate to run an amplifier at that level.

So this morning I set the Element X to fixed volume line output; that is, 100%. The Susvara played well at 50-60% on the SMSL. So although using fixed volume means I can’t control volume through Roon, the SMSL has a good volume control and its remote works fine.

So I think I’ll keep it.

 

[Noob]

That’s the difference between 83 and 99 dB sensitivity.

To quantify what I was complaining about, my Cayin iHA 6 is rated at 5-7 watts per channel depending on current output. With the Cayin at 50% volume, the Element X volume was usually at -20 dB.

On the other hand, to get reasonable volume at -20 bB required 95% on the SMSL.

Big difference. I hate to run an amplifier at that level.

So this morning I set the Element X to fixed volume line output; that is, 100%. The Susvara played well at 50-60% on the SMSL. So although using fixed volume means I can’t control volume through Roon, the SMSL has a good volume control and its remote works fine.

So I think I’ll keep it.

Why would you control volume at the dac?

I feel like I might be misunderstanding something. I'm guessing you probably were not using digital attenuation software, because then you destroy your bit-depth.

Higher end of the scale? What do you listen to?
This is my moderate listening level on 99dB sensitivity Goldplanar GL2000:

View attachment 114549

Keep in mind that the SU-9 runs about 2.8dB hotter than the standard 4Vrms dac so I would guess you might have your volume around 40ish with a standard output DAC like a Matrix Element X or Schiit Magnius.
Not sure how big the relay jumps are, but 1/2dB is pretty common. The jumps also may differ in size at different ends of the scale.

EDIT:

I just saw on the Matrix Audio website that the Element X is enabled with a very competent internal preamp that lets it go up to +10dB from the standard 4.5vrms output for a max of 15.8vrms. So you could just keep the sp400 on low gain all the time with the volume maxed and run the volume purely from your Element-X.

I guess you just never tried going over 0dB before. But the official specs say it has up to +10db so you should try it in preamp mode.

 

[Noob]

Hmmm you're right there is some interesting wording on their site regarding the volume. Makes me wonder if you're truly only using 99 of the 256 steps on the relay, and if so, why use a 256 step relay system if they can't be used?

We just need a software engineer to hack the software and unlock 256 volume steps, and extra gain haha.
View attachment 114584

The gain and relay shielding are both hardware concerns. So you would need an electrical engineer to hack it.

 

[Music1969]

Apologies if someone already mentioned but why does SH-9 have more power into 300 ohm load (unbalanced headphone output) ?

 

[cursive]

Apologies if someone already mentioned but why does SH-9 have more power into 300 ohm load (unbalanced headphone output) ?
View attachment 115613

Really comes down to design/build differences, the SH-9 isn't a fully balanced amplifier like the SP400. So while the SH-9 makes 226mw unbalanced at 300 ohms, it doesn't make any extra power using the balanced xlr headphone connector. The connector is there for convenience. On the SP400 the power does more than double when using balanced, you get almost 700mw @ 300ohms.

 

[Tks]

Well the SH-9 isn't a fully balanced amplifier like the SP400. So while the SH-9 makes 226mw unbalanced at 300 ohms, it doesn't make any extra power using the balanced xlr headphone connector. The connector is there for convenience. On the SP400 the power does more than double when using balanced, you get almost 700mw @ 300ohms.

I heard as long as you have balanced input, you can reap the lower chance of groundloops even when outputting to single-ended outputs (if the amp supports that, like the THX family of amps).

 

[Veri]

Apologies if someone already mentioned but why does SH-9 have more power into 300 ohm load (unbalanced headphone output) ?
View attachment 115613

Like cursive said, you are comparing an unbalanced amp (SH-9) to unbalanced output of a balanced-capable amp (SP400). When used with balanced headphones cables, the SP400 will pull ahead. Otherwise, the SH-9 (based on the SP200 design) will pull ahead in raw power.

 

[Inkey31]

Does this AMP deliver more consistent Voltage and Wattage out then the A90? It's less power right? Why do people say it's power supply is better thus delivering more power?

 

[Noob]

Apologies if someone already mentioned but why does SH-9 have more power into 300 ohm load (unbalanced headphone output) ?
View attachment 115613

SH-9 runs at a higher gain to compensate for not having balanced capability. The headroom should be the same in both, but sp400 needs higher input gain to get there.

 

[Noob]

Does this AMP deliver more consistent Voltage and Wattage out then the A90? It's less power right? Why do people say it's power supply is bette willr thus delivering more power?

Amperage, and therefore wattage is what is being referred to. Both amps can push pretty high voltages, but the sp400 stands out when driving low impedance loads because it can push huge amounts of current before clipping. And the power supply is a big part of this.

So yes, the sp400 is more powerful in an absolute sense because it has higher headroom to push voltages before clipping, but because it doesn't supply gain levels as high, the a90 will seem more powerful if fed the same voltages. The difference only becomes noticable if you feed the sp400 with a more powerful DAC. The A90 already reaches clipping with a 4v input, so it gains nothing from more input voltage, but the sp400 can be fed quite a bit more voltage and when this is done, it shows that it's true limits are actually a good amount higher.

Basically, if you get an sp400, get a higher voltage Dac to go with it. The Gustard A18 is a good option at 6vrms. The SU-9 is another good choice at 5.3vrms. The Matrix Element-x is a great (but expensive) option with up to a 15vrms output when used in preamp mode. You would probably be using the sp400 more like a power amp in that case and just leave it maxed on high gain while controlling output from the Element-x.
The RME ADI-2 DAC is another great option with a 6.9vrms max output. Not quite as high voltage but still a good step up is the Topping d70s at 5vrms.

Hope that helps. Basically, the answer is yes, it is more powerful, but you need higher voltage input to take advantage of that increased headroom. I think SMSL took this into account when designing their m400 and SU-9 DACs with a 5.3vrms output.

 

[jjluke]

I bought an SP400 for my birthday to pair it with Soncoz SGD1 DAC, after testing the SP200.

-Headphones/IEM: HD800s (ASR EQd in Roon) via XLR, HD580(no EQ) via SE, Westone 4(no EQ) via SE.
-Transporter: Odroid c2 with Roon Bridge via usb-c into SONCOZ SGD1
-Interconnects: DIY XLR-XLR with Neutrik plugs and audionote cable.

Just my impressions as I have no way to measure equipment.

Coming from a Ray Samuels HR-2 Emmeline, I first tried the SP200 and I was really surprised how good it sounded compared to the HR-2.
SP200 to me sounded more detailed and open with all my headphones/IEM.
However, HR-2(RCA-RCA) is dead silent at max volume with IEM and SP200(RCA-RCA) was not, with noise being an issue.
Moving to XLR interconnects from the DAC, the SP200 was completely silent.
After about 1 week of using SP200, I started experienced some fatigue with HD800s.

Left/Right volume was a bit of hit and miss as well, where sometimes the right was much louder than the left channel.
Other times, the same song was volume balanced on both sides.
I tried to play with the Soncoz's volume(digital?) instead and try not to touch the volume on the sp200, for some time, but really I did not like this workaround as I wanted to keep the source at its max volume.

In the end, volume discrepancy, fatigue and also the amount of heat that the sp200 was generating in XLR,
were the main factors for me, to look at the sp400. (Topping A90 is not available on prime amazon.co.uk, albeit the pre90 is.)

SP400 to me sounded more relaxed then the SP200, and I did not experience fatigue.
That for me translated to a better user experience.
Left/Right balance volume is also perfect, to my ears.

The HD800s sounds bold and nice at high gain in between 45 and 60 volume (12/1 o'clock) for DSD tracks and in between 30 and 40 volume (10/11 o'clock) for non DSD tracks.

As I apply EQ to the headphone via Roon, without EQ those volumes are even lower with the HD580.
I think the SP400 is an amazing headphones amp, it sounds really good, but I also think that it is an incomplete product, unless my sample is broken.

I was really disappointed to find out that the pre-out has no control.

I am not sure how I can drive 2 mono blocks in the living room with the SP400, if I also want to listen to headphones during quiet times.

More care could have been put, in the design and implementation of the overall package:
-no remote and/or software control for the pre-out: pre-out cannot be disabled.
-no manual and/or mechanical control for the pre-out: headphone plugged in does not disable pre-out, neither there is a physical switch for such selection.
-no usb port in the device, and/or WIFI (like SONCOZ) to update the firmware.
-no firmware upgrade path, albeit there is a specific entry in the menu about VERSION, showing 1.0 for both HW and SW, I guess this stays as is, unless you buy a new unit.

I haven't heard any other headphone amplifier as clean as this, it is a great sounding amp, and perhaps just this, justifies the higher cost, but I am sure there are many other amps that can sound as good as the SP400 and can provide an overall better package.

 

[Noob]

I bought an SP400 for my birthday to pair it with Soncoz SGD1 DAC, after testing the SP200.

-Headphones/IEM: HD800s (ASR EQd in Roon) via XLR, HD580(no EQ) via SE, Westone 4(no EQ) via SE.
-Transporter: Odroid c2 with Roon Bridge via usb-c into SONCOZ SGD1
-Interconnects: DIY XLR-XLR with Neutrik plugs and audionote cable.

Just my impressions as I have no way to measure equipment.

Coming from a Ray Samuels HR-2 Emmeline, I first tried the SP200 and I was really surprised how good it sounded compared to the HR-2.
SP200 to me sounded more detailed and open with all my headphones/IEM.
However, HR-2(RCA-RCA) is dead silent at max volume with IEM and SP200(RCA-RCA) was not, with noise being an issue.
Moving to XLR interconnects from the DAC, the SP200 was completely silent.
After about 1 week of using SP200, I started experienced some fatigue with HD800s.

Left/Right volume was a bit of hit and miss as well, where sometimes the right was much louder than the left channel.
Other times, the same song was volume balanced on both sides.
I tried to play with the Soncoz's volume(digital?) instead and try not to touch the volume on the sp200, for some time, but really I did not like this workaround as I wanted to keep the source at its max volume.

In the end, volume discrepancy, fatigue and also the amount of heat that the sp200 was generating in XLR,
were the main factors for me, to look at the sp400. (Topping A90 is not available on prime amazon.co.uk, albeit the pre90 is.)

SP400 to me sounded more relaxed then the SP200, and I did not experience fatigue.
That for me translated to a better user experience.
Left/Right balance volume is also perfect, to my ears.

The HD800s sounds bold and nice at high gain in between 45 and 60 volume (12/1 o'clock) for DSD tracks and in between 30 and 40 volume (10/11 o'clock) for non DSD tracks.

As I apply EQ to the headphone via Roon, without EQ those volumes are even lower with the HD580.
I think the SP400 is an amazing headphones amp, it sounds really good, but I also think that it is an incomplete product, unless my sample is broken.

I was really disappointed to find out that the pre-out has no control.

I am not sure how I can drive 2 mono blocks in the living room with the SP400, if I also want to listen to headphones during quiet times.

More care could have been put, in the design and implementation of the overall package:
-no remote and/or software control for the pre-out: pre-out cannot be disabled.
-no manual and/or mechanical control for the pre-out: headphone plugged in does not disable pre-out, neither there is a physical switch for such selection.
-no usb port in the device, and/or WIFI (like SONCOZ) to update the firmware.
-no firmware upgrade path, albeit there is a specific entry in the menu about VERSION, showing 1.0 for both HW and SW, I guess this stays as is, unless you buy a new unit.

I haven't heard any other headphone amplifier as clean as this, it is a great sounding amp, and perhaps just this, justifies the higher cost, but I am sure there are many other amps that can sound as good as the SP400 and can provide an overall better package.

SMSL has stated that there will likely never be a software update.

Also, I don't know why anyone would want a software update except for possibly adding new color options for the menu or maybe adding screensavers or wallpaper. . . Actually that would be cool. Maybe that is a good argument to make for a software update.

 

[w1000i]

Which amp has more power, THX SMLS, A90, the SA-1?

SA-1 will be better amp but to be used with balance output. it has easier tone as I compare it to L30, the SA-1 much smother and more comfortable to listen.

 

[Inkey31]

Has anyone tried this AMP yet with the Susvara's?

 

[cursive]

Has anyone tried this AMP yet with the Susvara's?

I just recently got the HE-6se from the Adorama sale. It has similar specs to the Susvara, but not exactly the same. The SP400 has more than enough power for my listening levels. Even using APO EQ with -5.5db I'm usually listening at 55-65 on the volume, sometimes 70-75, but that's really loud for my ears. What DAC would you be pairing it with? Because that voltage output makes a difference

My only gripe with the SP400 mirrors above post from jjluke - if they had just put a way to turn off the preamp out on the menu and or on the remote the amp would be absolutely perfect. The a90 you can turn off and on the preamp out, but then you lose the remote and relay volume, the gustard h16 has relay volume, but can't turn off the preamp out either. Seems none of the companies were able to squeeze that in for some reason.

Hopefully whenever the next round of these amps comes out they fix that one little issue, but I'm very happy with it otherwise. I purchased open box on Amazon from Apos so I paid about $520 which makes it worth it despite these drawbacks.

 

[paolomo]

I am late to the party because I joined the forum only a few days ago. I would like to thank everyone here: because of your reviews/comments I got this unit and it was one of the best purchases I remember doing in recent years

 

[foxxx0]

Quick question: Is the XLR Pre-Out *always* on even with the SP400 powered off?
I also have powered studio monitors that I feed from my M500 DAC and I would like to keep any potential HP-AMP powered off if not actively using.

Otherwise I might have to look for XLR switches.

Edit: Just found some more Information and apparently the SP400 has separate output stages for the Pre-Out, which means it needs to be powered and switched on in order for the Pre-Out to work, correct?