Review on 🔊 AIYIMA 2 Channel TPA3251 Digital Audio Amplifier, 175W + 175W HiFi Mini Power Amp, Home Professional Amp NE5532 High Power Full Frequency Class D Amp (Silver with Power Adapter) by Jack Harrell

I bought an Aiyama A04 amplifier for my Klipsch R-41M bookshelf speakers connected to an Aiyama Dac-A4 which I bought at the same time. With the Dac A4 I can stream Tidal and LDAC/AptX Hi-Res music from my Sony Walkman NW-A55, my Xperia smartphone and the Surfans F20 digital player. I also bought an Aiyama 24V adapter for the amp as it is not included. The amplifier requires an 18-36V power supply so it can drive a range of speakers of different power ratings. I also tested it with a 19V adapter with the same plug and polarity. You need to check the polarity and match it with the adapter before using, the middle is +. Of all the adapters I have at home, I've only had one that fits and works. I've found that most of my wall outlets are underpowered or have the wrong adapters. You will most likely need to buy one as well. It's a no-frills amp with a single black volume knob on the front and an on/off switch shaped like a light switch. The button and switch are metal instead of plastic, and the button has a lightly etched textured finish for a good grip. There is a faint blue light behind the volume control. The rear panel has connections for the RCA input only and an old-style (non-Toslink) digital coaxial connection. You can connect speakers with banana plugs or with bare wire ends. After soldering the ends of my 16 gauge speaker wire, threading it through the drilled holes in the connector is a bit tight, so I would recommend 18 gauge wire or thinner if you want to use raw wire instead of connectors. Tests I ran some tests including using the Aiyama A4 Bluetooth receiver - its USB-C DAC capability, and without the receiver using an old Onkyo cassette deck, a Sony MD player, a CD player and my Hi -Res digital player and my Sony smartphone. To connect devices with a 3.5mm headphone jack you will need an RCA to 3.5mm cable (not included). All devices and the bluetooth receiver worked perfectly with the amplifier and the sound quality was equally good without any difference. The 24V adapters could drive the speakers in the same way. To see if there was a difference, I swapped the adapters and streamed the same Tidal song using the Sound Meter smartphone app. At the 10 hour volume setting on the amp, readings ranged from 72-89dB, averaging around 80dB - almost identical results. . The sound spectrum and quality also seemed almost the same, imperceptible differences. Assuming there is a difference, I'll use a 24v adapter for better quality. Perhaps the 19-36V requirement is related to speaker efficiency - I'm not aware of that. Since there are no tone controls, I'm considering getting an Aiyama Dac A2 that plugs into a coaxial jack. This allows me to adjust bass and volume for different types of music. When I get it I'll add a Revain review. So what about the sound quality? The music is crisp and clear, with no coloration, muddyness, or distortion. What I immediately notice when playing Hi-Res music is a very dynamic, wide soundstage and almost 360-degree surround sound from just two bookshelf speakers. Compared to my Nobsound amp, I think the Aiyama can reproduce a wider dynamic range with a wider soundstage. The upside is a slight audible difference, but both work very well. I will use Aiyama as the main speakers and will use Nobsound when installing the speakers in the garage. Finally, a comment on performance, I would run at least 8 hours and it doesn't overheat, there is no line. noise or other problems. It's well built and solid, and mine didn't have any cosmetic imperfections or flaws. I hope my detailed review helps you decide whether or not the A04 is for you. I am very happy with it.