S.M.S.L SAP-4s Amplifier Review


Now those that know me know that i am very sceptical when it comes to using amps.  A lot of the time you see people using amps when there really is no need.   Not all iem's need an amp but what does need an amp is an ipod.  Some of you may know the amp section in Ipods are generally not the best  and in my case as my main player is a 64gb CF card Imod with caps inside an external amp is a necessity using a LOD connection.

With that said what amp to go for, how much should you lay down on this area of gear.   Well I will tell you it may not be as much as you think.  At home I use an 02 amp to me this is as good as it needs to get at almost any level it is almost ruler flat and extremely transparent.  On that go or away from my listening chair and 02 i have messed around with anything ranging from JDS labs, ibasso, Fiio, Headstage c&c etc and have came to the conclusion that amps are probably the worst area for the rule that the more money you throw at it does not necessarily mean your getting a worthwhile shift in performance.    

So here we have this little beauty (and what i think is the first review) the SMSL SAP-4s coming out of China delivered at a whopping £34.   Thats right £34, thats cheaper than most pre-built cmoy and even Fiio's popular E11.  The Sap-4s comes packing a max9722 amp this is something that is overlooked and has been around a while.  It was the MAX9722 aspect of this which got me curious and drew me in, since the first time I heard  a max equipped device I have been a fan.  So having spent a week with this already how does it stack up.


The SAP-4s comes in a rather plain white box with little on it bar the company logo, a simple instruction and the amp specs.  Upon opening under some cut out foam padding and presented nicely is the amp.  Underneath this is the accessories.  All in nothing fancy but very fresh looking and does the job.


The amp is £34 remember i wouldn't care if it came in a used carrier bag with nothing else.  However surprisingly you get a few extras in here.  You get a very nice SMSL interconnect (W2)  which goes on ebay for between £13-£15 shipped, a nice touch and if you do not need it you can always sell it for say £10 to offset the amps cost a little.  Next up there is a small leather pouch it has all the hole available and actually looks and feels excellent.  I am actually using it.  Finally there is a Micro usb cable but not the standard fare it is a white and black ribbon style and actually looks pretty cool.  Excellent from SMSL.


Build quality on the unit is stellar, it feels rock solid, the volume pot moves smoothly and the in/out ports give no pause for concern.  The on off swith is thin but feel solid and gives a nice click when locking into position.  The unit is made from brushed aluminium and looks and feels premium,  much more so than the c&c bh and the fiio e11. 

On the front you have (from left to right)/ on/off switch / output / input / volume pot.

On the back the charge indicator and charge port.

Simple thats it, no crossfeed, gain or bass boosts her just simple on off.  None of these i see as features missed bar in very specific situations a gain control.


Battery life was tested during burn in and from a full charge achieved almost 55 hours from constant play, I suspect this many be even higher if play time is stopped every now an again i practical use.  In any case this battery life is amazing and just seems to keep going and going easily you will charge it max once a week.

The highest impedance phones I tested with were both 150 ohm these being the Hifiman RE-262 and the Superlux HD-660 both were powered very well and no  clipping was reached I do not have anything at higher impedance but have no reason to doubt that it can power ever more hungry phones than those used.


In a word fun, the amp used with the pfe112 and se215 provided lots of it.  Everything was enhanced over say a stock clip HP out Soundstage grew as did separation, a slight bump in clarity over the c&c bh and Fiio e11.  

Treble is relaxed and shines without becoming fatiguing cymbals crash on the tracks like 1812 cannons and there is barley a hint of sibilance.

Mids are the strong point with the SAP-4s it sounds warm and lush clear and accurate, vocals such as Joan Baez Diamonds and Rust and Rodrigues Sugar Man are simply wonderful.

Bass is tight and energetic as I knew it would be as this is one of the particular characteristics i have noticed from all MAX9722 devices I have heard.  Infected mushrooms Legend of the black sharwama was the bass test track here and the SMSL came through with flying colors resulting in a smile on the face at the climax to when the bass drops.

In direct comparison to two others based in the budget amp section i would say it bests both the c&c BH as it is more lively and fun sounding with a nicer soundstage.  In terms of the FIIO e11 it smokes it in all departments of sound quality, in fact I am not the greatest FIIO fan it must be said (i have not yet heard the E12) as I dont really like the usual dark presentation in the e7, e11 and to and extent the e17 of which all have been or are currently in my possession.

Comparison to something like the c421 or even c5 is flawed as the specifically are trying to reach 02 levels of transparency.  The SMSL is does not seem to care about that but rather intends to make ones music sound enjoyable, it has a fun and energetic signature to it.


A reference amp the SAP-4s is not, however if I were to place it somewhere I would have it at the top of the sub £100 list as it stands, i just find its signature when pared with my imod to be immersive and rich.   This sound combined with brilliant build quality, stellar battery life and great accessories all for under £35 jus shows how hard some companies are working.  I believe the dac included version (TCG U-SKIN) of this will work with android phones and that too is incredible in its own right coming in at around £60.  

As for will I be keeping it after this review?  Absolutely I have not even looked at the c421 in want over the past week even though it is technically the better amp.  Theres something charming about the SAP-4s and at the price I can only recommend you give it a shot.

SMSL sAp-4s portable power headphone amplifier black