Didn’t expect much and thats exactly what I got awkward design with inputs and outputs on opposite sides making it not sit flat and not easily adjusted for gain control but all that really doesn’t matter considering the buzzing and low frequency humming that developed after about 20 hours of use. naturally my return date passed by 2 weeks save your money and spend it on a higher quality product

This is a little dynamo. Installed between tv and amp. The improvement to the volume and sound quality is fantastic. I have tried many other similar items for a much higher value and they are nowhere near as good as this.Very happy

"Mini Stereo Line Level Booster Amplifier Audio Preamp 20dB Gain Volume Control" fulfills every word of its title!Construction and finish are fine.As a preamp, it easily makes it into "hifi" performance. Maximum gain was about 20 dB. Measured performance using RightMark Audio Analyzer indicates 20-20k Hz frequency response that is very flat in the high end and rolls off gradually to -2 dB on the low end. Dynamic range is excellent, -93dBA. Total harmonic distortion is miniscule at 0.002 %, while intermodulation distortion measures 0.01%. These were measured using an ASUS/Xonar sound card and some of the specs are close to the sound card's limits.The only limitation that I see that could occur in some cases is that the output impedance is 100 kohms. If it is feeding an amplifier with low-ish input impedance, the audio performance could be degraded. Make no mistake: this is not capable of driving headphones, unless a headphone amplifier follows it to provide the required drive energy.The unit comes with a USB cable that can be used to provide +5 V power from a laptop or a cheap power adapter such as that used for charging many battery-operated devices. I haven't tested it with any other power supply, though it claims to be able to use anything from 5-20 VDC.Highly recommended to fulfill the need for boosting a line-level signal.

Pretty good sound and build quality, though a little bit expensive given it uses a cheap 5532 op-amp. Lower frequencies have more authority when running a 12v power supply through a supercapacitor array.I'm using this little guy to boost the preamp out from a Denon AVR-X1800H AX to my custom power amplifier since the Denon's amplifiers are not powerful enough to drive my Polk RTi A9s on their own without having to bi-amp them.The Denon's sound correction is enough to mostly overcome the 5532's deficiencies, but I'll probably try swapping the op-amp for an OPA2134P, OPA1656, MUSES02, or chifi discrete EQ200.

Exactly what I needed. Small. Perfect unit for hooking my Android phone to large speakers. Just buy a USB-C to AV cable I believe and you're good to go. Plug this right into the Amp, and you're good to go.Speakers > AMP > this unit > phone

No dislikes

This product does exactly what it says it does, it will boost your audio line signal by around 20 decibels. My own measurement put this at 17.2 DB louder from 15 feet away before you start to get distortion. It can go up to around 19 DB or so but you get distortion. Even 15 db is plenty to make a stock stereo in a car really loud, but be warned you won't be pumping mass bass as the power output isn't there to drive your Fosgate 12s for example, obviously anyone installing quality equipment like that won't be using this thing.The product is cheap and has multiple inputs and outputs available (see pro tips below). It also comes with a USB-A power cable so you'll need a USB-A port available or otherwise supply your own power.Many of the complaints about this product seem to be curable but do require extra work and or parts.Pro Tips on how to get this to work great:1. Take into account where you will be installing this. If you are installing this around unshielded cable, high voltage etc, because of its cheap nature, it will pick up a hum, this thing is not insulated at all really. It is best to keep it away from other devices and power it cleanly off a dedicated USB or power supply. See below for ideas how to fix if you get a hum.2. The 3.5MM input will be priority and no other inputs will work at the same time if you use the 3.5MM input, however, if you use RCAs and the 5-Din this thing will take in both and mix them evenly (There is no way to to mix or boost one more than the other). The output is both 5-Din and RCA, you can use either or both at the same time.3. Since this thing isn't driving that much power, I found even the cheapest cables work fine. Normally you want to use higher quality cables for the best sound with the least leakage but in this case we are going cheap, so even cheap cables will work.4. If you are installing this in a car, you're probably like me and installing it on an old or stock in-dash stereo and those are horrible for grounding and will usually pick up a hum because of ground issues so here is:How to fix the dreaded hum that people complain about:First, you can try to ground your stereo better if you can. This can help, but if you are just hoping to plug it in and not mess around try a Ground Loop Isolator like this: https://www.amazon.com/dp/B06XQYN77L?psc=1&ref=ppx_yo2ov_dt_b_product_detailsThe linked isolator uses the 3.5MM input on the amp and takes in a 3.5MM connection. An over simplified explanation is that by using an inductor that then creates a magnetic field, a ground loop isolator can essentially force any differences in current (caused by a bad or different resistance ground) to be nullified because this is what causes the hum. Please realize you'll need to get the correct kind of isolator for your inputs and outputs. Just search Ground Loop Isolator here on amazon and you'll find many. Since this isn't putting out that much power, cheap ones usually do the trick.Also keep in mind that there are two schools of thought and which one works for you depends on your situation:1. Place the isolator between the head unit (a stereo for example) and the amp. In other words place the isolator on the input side of this amp. This is the typical way of doing things and works for the vast majority of cases in car audio although not all.2. Place the isolator after the amp but right before the speakers if there are other components in the system like a game console, or another stereo component etc. This case is more specialized but you can pick up hum caused by the amplifier itself and it bleeds on the output side but this is less likely. The amp usually get's hum fed into it and you can eliminate that on the input side and the amp will output a clean signal.3. Place an isolator on the input AND the output side. This is really rare and only happens in extreme instances where there are a lot of electronics at play causing problems for one another OR there are powered devices after the amp that are picking up hum from the combination of sources. In this case you'd add one on the input side as close to the amp as possible, and then one on the output side as close the speakers as possible.Good luck! This thing is a steal at the price for what you can do with it using a little know how.

今回の商品は、非常に良い中古品との評価だった。少し前に同製品を新品購入したが、不具合があって返品した。中古品として価格が下がり、非常に良いとの評価で出品されていたので購入したものの、送られてきた商品は前回返品した商品そのものであった。製品箱もなく、あり合わせの段ボールの小箱に入れれれていたので、開封した時点ですぐに分かった。箱には数字の「17」がマジック書きされていた。前回のものと全く同様。返品商品を「非常に良い」と評価し、再販するのはいかがなものだろうか、、、？？？

It does boost the audio signal but it sounds different, very different. The audio output sounds Ok, but with all the high notes sortof muted. I fixed it in the amp but it should'nt need that.

Here is my application for this little amplifier:We are doing a Christmas program with preschool children up on a stage. I play their music from my ipad through bluetooth to 2 linked karaoke-type powered speakers up on the stage. I also have a bluetooth microphone, which has a receiver that plus into the aux line-in of one of the speakers. The problem is, whether using these bluetooth mics or wired mics (I've tried both), the microphone level on this speaker is not nearly loud enough. (The music can get MUCH louder than the mic.)So, I bought this to raise the mic volume. I am running the bluetooth receiver (for the bluetooth microphone) into this preamp, and then run a cable out of the preamp to plug into the 1/8" aux of the powered speaker.It boosts the volume quite well and I no longer have to speak really loudly while "eating" the microphone. Yay!However, using the supplied cable (1/8" to white and red RCA) I got a whole lot of noise. When I switched and used one of my own cables, it worked just fine, nice and quiet. Either I got a bad cable, or it was a fluke of some sort. But the main thing was that I got everything to work well today, and I hope when I go back tomorrow it will all still work fine. (I've had plenty of experience through the years of technology that works and then decides not to work the next day, so I'm still kind of holding my breath, haha. But so far so good.) So far, it has turned out to be just what I needed!!