Wikipedia
Yaqin (pronounced "Ja-chin") is one of the more prolific Chinese manufacturers of valve (tube) based audio equipment. They claim to have "engage in power amplifier research and production more than 10 years." Despite having several disadvantages compared to modern transistorised ( solid state) equipment, a valve sound is preferred by some commentators as having the most pleasing listening experience but has until recently been typically more expensive than transistorised equipment.
Yaqin equipment is primarily designed for a 220Vac mains electricity supply voltage. In countries with 230Vac such as the UK, some caution should be observed. Rebadged models have been offered for sale claiming to have dealt with the power supply issues. Unless you have a 240v version which is available by special order, then It’s wise to use a Variac (variable transformer) to drop the power to the required 220v for the UK, as some of the UK still receives 240V at the socket not the 230v it should. With valve equipment a 20 volt overload on the Mains input will result in about a 40 volt overload on the HT (High Tension) side. Use of correct input voltage is important. If in any doubt as to the voltage of your Yaqin, remove the cover from the power transformer, Yaqin typically stamps the primary voltage on the top.
The supplied mains lead have been identified as poor quality and sometimes not fused.
US and Canadian import models have been altered to operate from 110-120 Vac mains power.
Little reliable English-language data is available . Often comical Engrish translations exist, for example 'First class-B gall stone is combined , grade is SRPP circuit before the gallbladder. The wide speed is fast frequently, the sound is nice.' Having said that, 'gallbladder' is a mistranslation of tube or valve common to machine translation systems.