S.M.S.LSA300 HiFi Digital Amplifier, Infineon's MA12070 Chip Class D Power Amp, RCA USB Bluetooth 5.0 APTX Input, Multiple EQ Modes with Remote Control (Black)

Needed a compact and powerful enough amplifier to power up some Micca RB42 speakers and gave this a go. It performs flawlessly and provides more than enough power to the speakers without any audio issues. I was actually surprised how small it was. All the connections are nice and tight. Volume dial has smooth detents and menu is intuitive and easy to use. I also like that I can add a sub at a later time if I want. I’m not doing any special audio setups so this is perfect for my needs. Doesn’t heat up in my experience as well. Completely satisfied with it.

For near-field listening with bookshelf speakers (Micca RB42 and others), this amplifier sounds every bit as good to me as my old Carver 500W per channel class A/B amplifier. It is dead silent when the audio program is silent, and has ample power to drive the RB42s as loud as I care to listen with absolutely no signs of stress. The sound is very clean and pure with no faults that I can detect through the speakers I've tried it with.The power consumption is very low. It draws less than 1.5 watts when idle. When listening at levels I consider comfortable, the power consumption only rises by a few tenths of a watt. To increase the consumption by even a watt or two, I have to crank the volume up to the point where it is louder than I generally enjoy. When the amplifier is switched off, its bundled power supply draws 0.6 watts. By comparison, my old class A/B amp draws about 25 watts when idle, and the power consumption rises by 10s of watts at normal listening levels, easily going into the 100s when moderately loud.Due to the low power consumption and high efficiency of the SA300, neither the amplifier nor the power supply get noticeably warmer than ambient even when listening for a long time at levels I consider "loud". The enclosure has no ventilation holes, thus there is virtually no risk of dust or other contaminants getting inside. It appears to be very solidly built, and there is no reason to expect thermal stress or dust to shorten its life.One fault I found with this amplifier is that its bundled power supply uses a grounded cord and connects the electrical service's equipment ground to the analog audio input's ground. When using the analog input, this results in ground loop induced noise if the audio source is also grounded (for instance, an older style computer that uses a grounded power supply). For many applications, this won't matter, but it does limit the range of analog audio sources you can use without noise issues.Another minor fault for some applications is that the display is always lit, and cannot be shut off. It isn't too bright, but it would be for a room where I am sleeping or for a home theater if positioned where it is in view.There are many features I like about this amplifier. The speaker terminals are robust and can be comfortably screwed down on 14 gauge wire, and they also accept banana plugs. Bluetooth and USB audio sound great (no detectable flaws), as does the analog audio input when used with non-grounded sources. The bundled infrared remote takes two AAA batteries that are not included, so you don't end up with extra disposable batteries that you may not want. The amplifier itself is small and not too heavy (1.5 lbs), and the bundled power supply is even smaller, so it's fairly easy to pack it up and take it places. Bluetooth range, though I haven't tested its limits, is ample for my needs (at least to the furthest walls of my room). The display is functional and unobtrusive (nothing moving or flashing) and even lets you select different colors, but cannot be shut off. Volume is controlled in discrete steps (60 max) via either the remote or the knob which has detents corresponding to the steps. Pressing in on the knob accesses a menu via which tone controls, a few preset EQ modes, and other features can be accessed.The Bluetooth and USB audio inputs work perfectly with all sources I've tried including Ubuntu Linux. On Ubuntu 20.04.2 LTS, I had to install a sound output control application (named "Sound") to send audio output to the USB device, but the OS recognized the device right away with no need for additional drivers. The Bluetooth audio output from Ubuntu worked fine even before installing "Sound". The audio quality from Bluetooth and USB are equivalent (no differences that I could detect) when playing audio from Ubuntu Linux.Overall, I am very pleased with this amplifier. One minor improvement I can think of would be a floating power supply (so that grounded analog audio sources aren't affected by ground loop noise). Another improvement would be to allow the display to be shut off (for use in home theaters or rooms where people are sleeping). For what I am using this amplifier for (near-field listening at my computer desk, and occasional temporary setups in other rooms or out in the yard), it is perfect just the way it is.

The short version -Connect it to speakers, plug it all in, and it just starts working. Flawlessly, so far. Wonderful sound quality. Stupid easy set up and use. Some quirks that a techie-minded person may encounter.The long version -Received an unwrapped, open box (not taped shut) with a shipping label affixed. It's a miracle that it didn't open in transit and everything scattered. Box contained the product, well packed and insulated in high-quality foam (not Styrofoam). Product appeared undamaged in spite of the vulnerable packaging.Box open - it was nicely packed, included a remote, a white USB cable, a power supply brick (24v 6a, pretty hefty, which is what I wanted), a screw-on BlueTooth antenna, and a few small handouts. You'll need 2 AAA batteries for the remote, not included.There was only one hand-out with English info in 6-point type in light grey - very nearly unreadable. The English version was inside the fold, I had to hunt for it. It would have been nice to have a big obvious "start here" card that showed a basic connect-up diagram and basic instructions but I'm a techie so it wasn't hard to figure out; it's a pretty straightforward product design, see below.There was literally no detailed technical documentation on audio settings etc. included in the box or on the web site. The web site, apparently in China, is painfully slow, but lovely to look at, has an English section, and had a lot of good overview information on the product details page. There are no drivers or firmware updates for this product. The PDF manual is the same as the tiny little handout in 6pt grey included in the box.I knocked one star off due to the packaging / shipping and due to the lack of readable instructions, poor web site experience from a technical details perspective, lack of set-up instructions that are going to be clear to a less techie person. But frankly the product didn't deserve that as regards what it delivers, see below.The thing is so easy to use it doesn't need a lot of instruction. Power button. Input selector button. Volume knob. Connectors on the back are clearly labeled, high-quality speaker screw connectors that can handle banana plugs if you have them. Press the volume knob in and you get a menu, rotate to select entry, press the knob to select. Entries are clearly labeled. You can even set the color of the display, a nice little elegant touch. The display is small, but very clear and bright OLED and easy to read.USB audio works flawlessly out of the box, with one quirk I'll explain below. Plug it in, turn it on, and It just magically appears as a new windows audio device, no driver installation required. It just started working. Easy as that. That's what you would hope for, and that's what it delivered.The USB quirk is actually a strength, and really a Windows and iTunes thing, not due to the product itself. The short version is if you use iTunes and want to tinker with the bit rate settings directly on the speaker device, they have to match if you want to use Direct Sound.In Windows 10, go to Audio Settings > Sound Control Panel, click on the entry for the device (TX 384kb Hifi Type_C Audio). Click on Properties. Click on Advanced. The default is 2 Channel, 24 bit, 44100 Hz, a nice generic choice that doesn't assume too much about USB capacity.The max value is 2 Channel, 32 bit, 384000 Hz, highest possible quality (and highest possible USB bandwidth consumption, which matters if you don't have USB 2.0 or 3.x that can handle that kind of bandwidth, or other high use devices on the same bus, like a high quality web cam, etc). This feature was one of the reasons I picked this product.The default setting seems fine as Windows Audio appears to trans-code the bit stream (iTunes max is 24 bits). So everything I tried just worked. Probably why they picked that default setting. Duh.But if you tell iTunes to use Direct Sound, and you want to max the iTunes playback quality, then the default format has to be set to 24 bits, 192000 Hz max (matching iTunes) or you get no sound.I have it connected to a USB 2.x/3.x hub so I wanted highest possible quality settings. I made the adjustment from 32b/384k (Windows Session Audio) to 24b/192k (Direct Sound) and I'm not sure I can tell the difference to be honest. It still sounded fantastic, see below.As a matter of ego the OCD uber geek in me insists on having the highest possible settings I can have everywhere, so there's a bit of a prick to my ego, but whatever. More of an iTunes thing. Amazon Music (which one presumes uses the Windows Audio Session from a browser) had no issues with the 32b settings, and if I'm willing to use WIndows Session Audio from iTunes I think I'd be happy to check the "best settings everywhere" box in my head.To try it out, I initially connected it to a pair of Polk T15s, which are a nice-ish pair of small bookshelf or desktop speakers, about 6x6x10 in, solidly built, which have a dome tweeter, small-ish base driver, and a ported enclosure. In the past I've regarded them as "OK but not great" compared to my trusty, beloved, battered, ancient Boston Acoustics A70s. I just wanted something basic to test connectivity, function, etc.But I have to say... wow. Just wow.The imaging, the precision, and depth, the low end clarity, the base in particular (without EQ adjustment). It was utter audio joy to listen to even on those dinky little speakers. And this is by comparison to a very nice pair of over-the-ear Seinheiser earphones to compare best possible sound from other DAC sources, like my laptop RealTek sound chip. They just don't compare. I can never go back.It just sounds beautiful, like I remember high end audio is supposed to sound. It's been a long time to get back to the clarity and detailed sound I could get from something like an Infinity EMIT tweeter and a high quality amp back in the day. I've always been a fan of D-class amps, but now I'm completely sold.Seems to me I have a whole new set of speakers. I've been cycling through various familiar music, and I am completely surprised by some of the sounds I never noticed before. It's that noticable.I also use the speakers for video conferencing audio. The irony is that I can now hear the echos and hollow sounds (and dogs barking, etc.) made by poor acoustics in various home offices that more clearly. It actually helps discern what people are saying by helping differentiate the sounds.I picked this unit because of its simplicity, its 32 bit DAC, it's attractive build, the good reviews, and the fact that it would take a high bandwidth direct USB audio stream. It has delivered beautifully on all counts. Moreover, it's made me aware of just how mediocre the sound quality is from various sources, BlueTooth devices, etc.On that point, I've always regarded BlueTooth as a lower-than-best audio source but tried the feature out anyway in the spirit of a complete review. I paired it with my laptop without difficulty, but I had to unpair it from my iPhone first, otherwise it didn't show up as an available device. iPhone pairing was seamless and produced about the audio quality I expected from an iPhone source.From Windows 10, the Speakers Properties > Advanced tab shows that it's paired at 16 bit, 44100 Hz "CD Quality" which I regard as a step down from the USB settings I tried above, and is less than the 24-bit quality iTunes can produce from downloaded music bought from their store. I could discern the difference - muddier, loss of detail, etc.But I'm sitting directly between two very high quality speakers and testing the same high detail music side-by-side, A/B etc. In a backyard or a larger room with other ambient noise it would be difficult at best to discern much of a difference nor is it likely that you would care in those circumstances. And this is not an issue with the product, but with BlueTooth audio itself. So I'd say it worked as expected, i.e. flawlessly.In a similar vein to the USB experience, Direct Sound again didn't want to connect using the higher bit rate settings, so I just dropped it down to Windows Session Audio, and heard the expected blurry BlueTooth music.There was a whole level of echo and resonance missing from Sean Shibe's Bach on Acoustic Guitar. Very discernible to me. But not the device's fault. Let's be clear. BlueTooth is never (IMO) going to be an audiophile audio source, but it's more than good enough for big rooms, more typical audio systems, or situations where such overly discerning tastes won't matter.So I'd say the BlueTooth worked seamlessly, from two different devices, produced as good a sound quality as I could expect from the source, which is about as good as it gets there I guess. Personally I'd say a 32-bit DAC is overkill for BlueTooth audio, but it's a nice feature to have for flexibility in a audio/video room setup.All in all - product is clearly 5 star quality. I had an odd shipping experience, I hope not the norm. The out-of-box experience wasn't ideal but it wasn't bad either, in part because the product is well designed, clearly labeled, and does the specific things it does and little else. I believe it's overkill for a BlueTooth source, but for direct or USB audio, it has very high precision, clarity, rendering, etc., all that I'd want in a DAC and an amp. The 32-bit DAC and precision D-class amp electronics claimed in the product description appear to deliver exactly what I wanted.I literally couldn't be happier with the choice.So there you go. Go spend money.