This preamplifier has tone control functions and adopts class A power, sound extremely delicate, slender high-frequency, low frequency plump and elastic, if use top op amp IC like as OPA2604 or LME49720, it will achieve perfect sound. Specially, it used a R-type audio dedicated transformer. And it has direct access function; you can skip tone adjustment to achieve original sound completely.
When audio sourcing record, speaker unit, placing the device is not necessarily perfect, and if your preamplifier adopt pure straight, it may not be able to meet the demand. At this moment, add tone adjustment function is very important. If you no extra power supply equipment, passive preamp tone is preferred, which can enhance the effect of high and low frequency is obvious.