SMSL sApII TPA6120A2 Big Power High Fidelity Stereo Headphone Amplifier Golden

Recently went looking for a small non-obtrusive amp just to power some phones for TV and incidental listening when not engaging the Bryston BHA-1 head-amp.

 
Well just got this little guy, I knew nothing of S.M.S.L. but it looked like the SMSL sApII TPA6120A2 should fill the bill so thought I’d take a chance.

 
Needless to say it’s a phenomenal little amp, plugged in my Fiio X3II from the fixed line output, way more than enough power to get the AKG K7XXs boogying at 10-11:00 o’clock on the dial with plenty to spare. Well power is not everything and I was presented with excellent separation and air, base is full and deep and highs are IMHO super clean and extended.
Starting with the almost 1/4" thick front face plate, build quality belies the budget price, it's a classy solid little unit.

 
Going by the online photos it looks like they’ve changed the 24v power supply, which is now about 2/3rds the size of the amp. Even with my Senn IE800s iem’s there was zero hiss or noise when the volume is maxed out (without music playing of course) which is a testament to an excellent designed amp/power supply.

 

 
So overall a very highly recommended little amp that should fit anyone’s budget and power about any phone.
 
...Just to add...believe I'll be using this little guy to listening to more than just TV... 

I got the SMSL SAPII Pro HeadAmp by mail and costed me about US$50.  5 days ago.
Thanks to Head-Fi  Website for my collections of reviews of a number of China brands Head Amps: FiiO, Topping..
Since I have a 1955+  DAC by SMSL,  I have confident in SAPII (PRO Version). The SMSL are looking as a triple set on my desk ( I also have the SMSL SA-98 Digital Amp.)
My setup is :  USB from Foobar2000 media player  in  i-5 Windows 10 Asus Desktop computer to SMSL 1955+ DAC and  RCA to SMSL SAPII Pro.
My monitor is AKG K701 - bought just 2 weeks earlier. 
My music world: mainly classical, plus cinema sound tracks, some jazz and female vocals.
The moment I plugged the power of the HeadAmp, I was shock by the chassis vibrations.  The Amp was like a vibrator when I placed my palm on the top plate!!
Since there was no smoke ...so I watched it  and let it power on with no music source for an hour.
When 1 hour was gone, I placed my palm again on the top plate, I felt a little warm and the vibration was still there but less vigorously as the first minute.
Well, to tell the story short, At about 5 hours of burn-in of the HeadAmp  and there was NO MORE VIBRATION.
It is now after 20 hours burn-in, I would like to tell the SAPII Pro is doing its job:  Big power to drive K701.   The clarity,  soundstage, sound quality with or without the SAPIIPro are ALMOST THE SAME --- It just amplifies the source as a straight copper wire. I checked this with my other headphones: Philip SHP895 and JVC HA-SBT200X cabled with little volume level from SAPIIPro.
The 2 headphones are now much inferior than the K701 + SAPIIPro  setup. much behind by MILES..
I believe my (powered) headphone listening experience will be further improved along with the burn-in.  
I am totally satisfied with the SAPII Pro. I may be more happy man if SAPII has the Bass Boost, like some FiiO models, just 1 click for different sonic signature  headphones .   
China is the world factory making many products with name brands from all over the world and its own name for 20+ years. Some have their qualities, especially electrical characteristics, not very convincing before but are improving. If we do more search and resourcing before buying, we can buy good products from China.  They are about 10 times cheaper than many TOTL HeadFi equipment with COMPARABLE Sound Quality and Build quality!!
 
I may post further review after a month with my HeadFi gears are further burn-in.  
 
  
 
 
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I bought the SMSL sApII as a stop-gap after my Little Dot MKIII failed after 5 years of use, five hours a day. No complaints there! I just don't have the money to upgrade just now!
I have invested in some great tubes for the LD MKIII and, plan to buy another one as soon as possible.
So, in the meantime I'm using the sApII with it's supplied PSU.
My front end is a PC running JRiver Media Center 21 playing FLAC files via WASAPI to a Musical Fidelity V-LINK to a V-DAC via SPDIF optical. The V-DAC is battery powered.
Headphones are unmodified Sennheiser HD 600's.
The SMSL sApII is an absolute bargain for the price. If it was made in the USA or Eurpoe then I'm sure it would cost 3 times the price!
The bass is slightly lacking in precision and depth and there is some harshness in the mids and treble when pushed slightly. Soundstage is okay but nothing special.
I really don't know how SMSL can make these for the money?
I'm sure that this would be a very good place to start for a cheap entry level headphone amp. I rarely go above 25 percent volume for my HD 600's.
I forgot to mention that there is no noise whatsoever on my example.
Hope this helps,
 
Rich.

I bought my SMSL sApII on amazon.co.uk market place. The vendor was SHENZHENAUDIOUK, the item was shipped from China and I paid £32.39 (US $50 or €44). There was no delivery charge.

Reasons for purchase:

my Dell Vostro Core i3 desktop has integrated audio with slightly low output level. Amplification reveals some EMI noise. Previously, to have a clean output, I'd been using a FiiO E7 (portable USB powered DAC+amp combo) which is nice enough but I have got really bored with pushing little buttons for step changes in volume instead of just twirling a normal rotary dial. Also I recently bought a Samsung Tablet and a Samsung dock with proper fixed level Line Out and wanted to use the FiiO with that (and occasionally with my ancient iRiver H140's Line Out, or my Eee PC netbook). I already had a HiFimeDIY USB DAC (el cheapo version of ESS Sabre) so I just needed a cheap desktop amp with power supply. I'd read some very positive reviews of SMLS products but also some criticisms of build quality. At £32.39 I decided to risk it.

It arrived in good time. Packaging is perfectly adequate to protect the items and not fancy at all. I got the amp, a power supply with UK plug, a 6.3 to 3.5mm headphone jack adapter and whatever small print usually comes with electrical items suggesting they probably won't burn down your house and may even be recycled...or not...I don't recall. I recycled the paper and card. The 6.3 to 3.5mm headphone jack adapter is big and not exactly pretty but also it doesn't have to be. It works. If you need such an adapter you might as well use it.

As mentioned my core set up is: PC>USB DAC>Amp. Input is music (flac derived from CD, usually rendered by mpd or a UPnP renderer), movies and all the usual crap that passes through a desktop PC, from internet radio to podcasts to games to badly lit but astonishing feats of bedroom athleticism and endurance. uh uh oh. Headphones range from Sennheiser Momentum (circumaural, 1st generation) through Koss KSC75 and Samsung dual driver IEMs and Shure SE215 and Xiaomi Pistons. I no longer have any high impedance headphones. Every earphone and headphone I currently own is designed for portable use. I hadn't really realised this until thinking I ought to try the amp with a traditional domestic headphone and then remembering that my last pair of moderately high impedance 'phones (Senn HD) died on me about a year ago and I had never felt the need to buy an exact replacement - I bought some Momentums and they make for a perfectly good substitute imo and also work beautifully with my phone and tablet.

The amp is fine. It has more than enough power for any headphone designed for portable use. I assume it could easily drive headphones with 250-600 ohm resistance. I rarely get the volume knob even one third of the way up, even with choral or classical music with great dynamic range. There are no weird noises. Smoke has not been sighted. There have been no sparks or flashes. It just amplifies the signal and seems to do it perfectly well and unremarkably. It can get warm. Not hot, just warm.

Given a typical, modern, highly sensitive headphone I'm not sure that my ESS DAC + SMSL amp sounds particularly better, worse, or different to my FiiO E7, but it certainly packs a lot more power and is more convenient (simple toggle switches for on/off and input, and rotary dial for volume). I definitely prefer its output over my Galaxy Note's and Galaxy Tab's earphone outputs. Bear in mind that these are not bad performers and are among the better phones and tablets for audio (measurably so, see sites such as gsmarena for consistent/comparable measurements of the audio output of these kinds of devices). With my Koss KSC75 (only 60 ohm capacitance but much less sensitive than modern designs) the low output levels of the phone and tablet becomes apparent and the SMSL amp is obviously better.

Conclusion:

It was £32.39 well spent. I'm not tempted to upgrade the amp but now might be tempted by some better headphones that a typical PC or portable amp wouldn't be able to drive nicely but which the SMSL should drive very easily.

edit: (one month later) I noticed another reviewer found the RCA inputs reversed. I've now used my SMSL sApII with RCA inputs as well as the minijack input and I don't have this problem. It's actually really convenient to have dual inputs and a simple toggle switch on the front, as I can have my PC+ESS DAC permanently attached to one set of inputs, alongside another cable that can go to my Galaxy Tab dock or iRiver H140 Line Out (proper Line Out not a headphone jack).

So a month after purchase I am really pleased with this product. If anything changes I'll update again but I think I'd recommend this to anyone who needs a great value headphone amp on their desk.

This is my first amp so bear with me lol.
 
I bought this from ebay with minimal fuss and didn't have to wait long. I quickly plugged it in and had a listen, first thing I noticed was the audio sounded weird, soon worked out the RCA inputs are marked wrong, even the colours are wrong but not a serious problem just a quick switch around (the 3.5mm input is fine).
 
The second issue I had was with the 3.5mm to 6.3mm adapter, it must have been a low quality job as any movement caused the audio to corrupt, threw the adapter away and plugged one of many I had laying around.
 
The sound quality is very flat and hardly changes from my Xonar DS (LME49860NA). I could say it feels a little brighter but only seem to notice it in foobar2000.
 
To be honest I didn't really need an amp for my RX900's or the 668B's (although the 668B's were causing me problems) but having the convenience to manage my headphones on my desktop is bliss.