Why I buy this one ?
- Four channel stereo headphone amplifiers
- Maximum output power on each channel regardless of different headphone impedances
- Four 1/4-inch stereo headphone outputs
- Individual volume control for each headphone output
- Stereo 1/4 inch input connector

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What our customer's say!

"EXCELLENT HEADPHONE AMP WITH SOME PHONES, BAD WITH OTHERS. (wish I could re-rate to 3 stars)", I have revised this review on August 9, having found a problem. Another review suggests that this amplifier is of poor quality, this is not what I found. If you have high impedance phones, such as AKG K 240 Monitor (600 ohms) This amp will be totally useless. However if your phones are low impedance, such as the newer AKG K 240 Studio or K 240 MK II (55 ohms) performance is excellent up to about 98 dB SPL. This is a level that is quite loud and above the safe limit for extended time periods. Performance with phones of less than 55 ohms is unknown.

Without knowing the circuit topology, I will not attempt to predict performance on very low impedance phones.

High impedance phones require a higher voltage at a lower current than low impedance phones. Amplifiers that can power all phones well have to supply both voltage and current at high levels, leading to wasted power and heat. Heat sinks and power supply thus have to be bigger, ie, more expensive. Sampson has made a choice to limit the voltage output of the S- Amp to produce a cool running unit. There are plenty of amplifiers that will not produce enough voltage for the AKG 600 ohm phones. AKG thus reduced the impedance of the K 240 phones to 55 ohms around 2004, or so, in response to the trend toward lower voltage headphone amplifiers.

Headphone efficiency also is important. Efficiency is typically listed as SPL (sound pressure level) at one milliwatt delivered to each channel of the phones. Comparing voltage sensitivity of phones of different impedances requires some math.

Performance of the S- Amp with the AKG K 240 Studio 55 ohm phones is excellent. I listen to opera, symphonic, piano and some rock music. Sound is full and free of colorations.








"A great product with the right cable used", For $50, you do get an excellent quality headphone amp which can be used anywhere, and the best kind of cable to actually use for the headphone output to get into the amplifier is low-noise mic and instrument cable with 1/4" stereo jacks on each end, 3 feet is sufficient for most purposes), and if a 3.5mm mini jack is required, a 1/4" STEREO JACK TO 3.5mm STEREO PLUG ADAPTER is readily available anywhere, and this even makes my Sennheiser HD 520's sound clear anywhere. The 4 separate inputs allows you to control the volume of each individual pair of headphones used.

"Horrible Unit, Poor Quality", I own two of these units, I use one for my home PC to mix outputs to my speakers and two different sets of headphones (one is a headset), and the other for my audio studio. Both units have serious problems with hum and crackle. They are very poor amplifiers distorting the output in a way that makes listening to music quite unpleasant at times.