SMSL SP400 Review (headphone amp)

[Red@]

I don't know, what is going on with the unit sent to @amirm .
But as with other users here, the smsl does not deliver in terms of volume.
I have a Gustard x26Pro (vivid filter) feeding 5.1V to the SP400.
To listen to my new Susvara, I have to put volume in 99% in High gain, and I still don't feel it's enough.
Following @amirm , it should have been able to drive the susvara.
In the other thread here related to the SP400. @SMSL-Mandy said that they are designed to drive headphones ranging from 10 to 600 ohm. But it is not about ampedance, it's more about sensitivity Aka. voltage.
@SMSL-Mandy can you please fix this ? Should I return my unit ?

 

[Roland68]

@Red@
Do you use the RCA or XLR input on the SP400?
Please measure the output voltage at the SE headphone output at 1KHz, high gain and volume 50. Then you could compare the values with other SP400 owners.

 

[Red@]

@Red@
Do you use the RCA or XLR input on the SP400?
Please measure the output voltage at the SE headphone output at 1KHz, high gain and volume 50. Then you could compare the values with other SP400 owners.

XLR balanced all the way

 

[Roland68]

I just looked inside my SP400, the board is Ver. 1.3.

WARNING! to all SP400 owners who want to open their device.
DO NOT try to remove the base plate first, you will destroy your SP400.

If you want to open your SP400 (at your own risk, of course), you must first remove all 6 screws from the base plate (including those under the rubber feet) and then pull the shiny top off with a suction cup.
The rest should then be obvious.

 

[Roland68]

I have just measured with a 1 KHz signal, fed by the Gustard A18 MQA version with volume 00dB, SP400 volume 50, cabling balanced.
The output voltage from the A18 should be max. 6 volts.

Voltage measured at the SE output:
Low Gain = 0.335v
Middle Gain = 0.493v
High gain = 0.610v

This is a very moderate gain, I know amplifiers with significantly higher gains, but that can also cause other problems.

My most power-hungry headphone is a Fostex T50RP MK III. . With high gain I reach "my" maximum volume on the SP400 at Vol. 72, with low gain I need Vol. 82 for the same volume.

 

[Red@]

Oh my, I thought Abyss has a stellar reputation in the industry for being the end game. I really hope this is only the case to Diana not 1266 TC. I upgraded the cable to their recommended superconductor cable, it smoothed out the treble a bit but it didn't help with the overall dynamics. It still sound muffled maybe due to the weak amp. Do you know if there is any way to submit an inquiry here for the admin to review it?

No they are muffled due to their Frequency Response. It is all over the place

 

[Red@]

Even though this is controlled by program, I don't think SP400 has the means to upgrade it. So not helpful. But I say why bother where the number is at if it's loud enough.

It is not loud enough !

 

[Red@]

The gain on SP400 is a bit low. So it needs a bit higher DAC voltage it seems. It's kinda similar to L30 situation.
My take is that in real world use it doesn't really matter unless someone actually max it out and still doesn't have enough loudness.

My case with a susvara. Maxed out but not nearly loud enough (x26pro xlr to xlr)

 

[Explorer]

Excellent DAC/amp. Sounds the same as my L30 (transparent) but I like the handling of it more

 

[Music1969]

Lots of new gear coming each month but this is still a killer headamp

For most people (that need a standalone headamp) probably the last you would ever need

Subject to any quality / reliably issues but I haven't seen any reported

 

[Music1969]

My RME can output 13dBu (3.5Vrms) and 19dBu (7Vrms)

7Vrms won't / can't cause the SP400 input to clip?

What is the input voltage limit for SP400?

 

[gvl]

I'm using one of these with its complementary M400 DAC since some time ago. My HD6XXs never had so much clean and deep bass. The sound has that proverbial warmth, clarity, and non-intrusive details that I struggled to achieve before, and that is w/out any EQ. I don't have to convince myself that I like what I'm hearing, because I know I do. The upgradititus will eventually set in, but so far it seems I finally found my end game desktop setup. The inability to turn off headphones vs. line outputs and vice versa is a downer, but I'll figure something out.

 

[Music1969]

so far it seems I finally found my end game desktop setup

Me too. I can't see (hear) any need for another headamp for many years.

 

[gvl]

Me too. I can't see (hear) any need for another headamp for many years.

Let's hope they last The amp tends to run fairly warm.

 

[Music1969]

Let's hope they last The amp tends to run fairly warm.

Hehe yes reliability is only question and it's still too young for anyone (even SMSL) to answer. Will give an update in 5 years

But this isn't their first headamp, so they have lots of experience.

Mine is only a little warmer than my RME ADI-2 but less warm than my Mac Mini !

But my Focals are easy to drive. Maybe it would get warmer driving difficult cans to loud volumes.

 

[gvl]

Mine is warm just from sitting idle. It seem to radiate enough heat downward to warm up the DAC under it as well. I can't say it's alarming but it's warmer than what I had before. Maybe I should drill some vents in the Plexiglas cover

 

[Music1969]

Mine is warm just from sitting idle. It seem to radiate enough heat downward to warm up the DAC under it as well. I can't say it's alarming but it's warmer than what I had before. Maybe I should drill some vents in the Plexiglas cover

If you seperate DAC and headamp (i.e. don't stack them) does it improve?

Mine are not stacked.

 

[gvl]

If you seperate DAC and headamp (i.e. don't stack them) does it improve?

Mine are not stacked.

It should and I may end up doing that. The DAC runs cool by itself.

 

[gvl]

Side by side the DAC is much cooler, but the amp is about the same maybe 1C less at 40C. Not too bad but plastic top is not a good idea, should have been aluminum for better heat dissipation.

 

[Roland68]

Side by side the DAC is much cooler, but the amp is about the same maybe 1C less at 40C. Not too bad but plastic top is not a good idea, should have been aluminum for better heat dissipation.

The cover of the SP400 consists of a 2.5 mm aluminum plate and a glued approximately 0.7mm thick black plastic plate. Maybe acrylic?