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gut

I bought these amp modules to build a series of headphone amplifiers but unfortunately the output grounds of each channel can not be connected together without damaging the circuitry (class D amps!). I tried the mod of using a 20uf (or larger) isolation capacitor on each output +ve but this introduced too much distortion. As a low output stereo amplifier used with speakers, they put out an acceptable listening level. The problem is the high level self noise, an audible hiss. In a quiet room with quiet passages of music or when the music stops, the hiss is easily heard. The volume control has an odd effect of the noise level. The mid position gives the least noise, but close to zero and at near full output, the noise increases. The on-off switch causes a loud crack heard through the speakers when turning on the amp. I'm a little disappointed with the performance of these amps, but they were inexpensive.

I bought these amp modules to build a series of headphone amplifiers but unfortunately the output grounds of each channel can not be connected together without damaging the circuitry (class D amps!). I tried the mod of using a 20uf (or larger) isolation capacitor on each output +ve but this introduced too much distortion. As a low output stereo amplifier used with speakers, they put out an acceptable listening level. The problem is the high level self noise, an audible hiss. In a quiet room with quiet passages of music or when the music stops, the hiss is easily heard. The volume control has an odd effect of the noise level. The mid position gives the least noise, but close to zero and at near full output, the noise increases. The on-off switch causes a loud crack heard through the speakers when turning on the amp. I'm a little disappointed with the performance of these amps, but they were inexpensive.

I bought these amp modules to build a series of headphone amplifiers but unfortunately the output grounds of each channel can not be connected together without damaging the circuitry (class D amps!). I tried the mod of using a 20uf (or larger) isolation capacitor on each output +ve but this introduced too much distortion. As a low output stereo amplifier used with speakers, they put out an acceptable listening level. The problem is the high level self noise, an audible hiss. In a quiet room with quiet passages of music or when the music stops, the hiss is easily heard. The volume control has an odd effect of the noise level. The mid position gives the least noise, but close to zero and at near full output, the noise increases. The on-off switch causes a loud crack heard through the speakers when turning on the amp. I'm a little disappointed with the performance of these amps, but they were inexpensive.