SMSL AD18 HIFI Audio Stereo Power Amplifier with Bluetooth Subwoofer Output

===EDIT===Despite the product description claiming it's supported, there is a problem with this amplifier and the 96kHz USB sampling rate, where every so often the speakers will output a deafeningly loud cracking/hissing noise. This can be resolved by setting the sampling rate in windows back to the default 44.1kHz sampling rate.==========I bought this wanting a compact, Bluetooth-enabled amplifier that would compliment my Wharfedale Diamond 220 speakers without breaking the bank while also not being so incredibly cheap the quality is in question.I'm a student so the limited space of my student bedroom meant I was looking for something with a compact package.I managed to get a relative bargain by getting a customer return from the Amazon Warehouse, thankfully it was in perfect condition as I've found the warehouse to be a bit hit-or-miss.The unit has loads of connectivity, I opted to use the USB connection (configured at 96kHz) from my laptop as this would bypass my laptop's sound card and instead send the digital signal directly to the amplifier.I connected my speakers up with some speaker cable bought from Richer Sounds and some soldered banana plugs from Amazon.I'm very happy with the sound, my speakers are rated for 50W each and this amplifier can go up to 80W per channel. This amplifier is **loud**, and I've gone nowhere near the limits.The proprietary 'SDB' EQ mode makes for a good listening experience, I also did a +2dB bass offset because I don't have a subwoofer (although there is a port for connecting an active/powered subwoofer in the future). I'm no audiophile but I think it sounds pretty great!The Bluetooth interface supports APT-X, a low-latency audio codec. My phone and laptop both support this, I think it sounds fantastic too. This is great if I'm watching movies in bed from my laptop as I can avoid using my laptop speakers, I do notice a tiny bit of lag where the audio is behind the video. (With VLC video player you can set a delay on the video if this annoys you).The display is good for configuring the amplifier, it works well and is intuitive enough.The remote is nice for controlling the volume and settings from in bed, however, the remote leaves a little to be desired...Sometimes the amplifier doesn't respond to button presses on the remote, so you have to press 'A' to sync it back to the amplifier. The remote won't allow you to change to modes without direct sight of the display because there are no buttons like 'Bluetooth', 'Aux', instead there's a button for switching between inputs, but you can't tell which is selected without sight of the display. If I'm in bed and want to switch from 'USB' to 'Bluetooth' it's hard to read what the display is set to from that distance.Overall I'm really pleased with this amplifier. It's small, affordable, well built, sounds great and has great specs.

I've been wanting to upgrade the sound system for my PC for a while and have been pondering whether to go for powered speakers or Amp driven ones. Having found this little Amp and its good reviews I thought i'd go down the route of Amp driven. The set up is from the computer sound card into the amp and onto the Wharfedale Diamond 9.1's. The power the amp supplies is plenty to drive the speakers comfortably at low and high volumes and it sounds as good as an entry level Intergated separate amp so the price of £122.99 seems reasonable.The Amp comes with a power supply that looks similar to a standard PC type PS, but this one is a 24V 5A - which makes the claim that the amp is 2 * 80 watts unlikely, as the max power consumption is likely around 120 watts. 20-30 per channel is more likely, but even so it still packs a punch and is perfectly good for a PC/TV set up where space is a key consideration. Aux from the PC, Optical from the TV tested and work well, and I've just tried Bluetooth and my Huawei P10 Lite connected first time and the sound is good. I've included the User Manual for those interested in the technical data and operation.The headphone output is okay, but as others have noted it does have a limited output, so if you have high impeadance phones and want to listen loud you may want to think about a headphone preamp. The remote control - it works and does the job, but not exactly elegant.Overall though i'm really pleased i went for this set up over powered speakers

I'm using this coupled with a pair of Denon bookshelf speakers and a Yahama subwoofer. It sounds pretty good for a tiny, cheap amplifier. Compared to the full-size Denon amp I was using until now, the bass is a bit weak from ordinary speakers, and it really needs the subwoofer to fill out the low frequencies. In addition, the middle frequencies sound a bit harsh to my ears but, again, that's in comparison to my previous amp.The USB input appears as a USB soundcard, and does need any specific drivers on my computer. The Bluetooth connected to my Sony phone without difficulties, and was recognized as an AptX device.The unit is smaller than it looks in photos -- about the size of a house-brick cut in half lengthways. It needs an external power adapter, which is about the same size. I was irritated to find it was supplied with a European plug, not a UK one. This isn't a deal-breaker, but it means adding a couple of quid for an adapter or a replacement plug to the cost. It is supplied with a short USB cable which is, oddly, white. There is an external Bluetooth antenna -- presumably because the all-metal casing would prevent an internal antenna working.Geeky technical note -- this unit uses class D amplification. This means that the amplitude of the output signal is controlled by pulse-width modulating (PWM) a current which is either fully on or fully off. Thus negligible power is dissipated in the final output stage which, presumably, is why the unit can be so small. It also means that no separate DAC is needed for digital input signals -- the digital sample values are converted directly to PWM duty cycles. It also means that the analog input has to be converted to digital. There is therefore no conceivable benefit to using this unit with an external DAC feeding the analog input, as is the case for many traditional class-B amplifier designs.Class D amplifiers do tend to have a characteristically "digital" sound -- bright and a little harsh. However, the signal-to-noise ratio is impressive, because there is no analog processing whatsoever.All in all, a good purchase, if you need a very compact amp with direct digital inputs and a subwoofer output.