目测应该是输出变压器坏了?老的670输出变压器用的是Triad变压器(Primary - 20K ohms at 12.5 milli-Amps (or) 5k ohms at 25 milli-Amps Secondary Settings - 600 ohms at 0 milli-Amps, 250 ohms at 0 milli-Amps, 150 ohms at 0 milli-Amps & 62.5 ohms at 0 milli-Amps),也可以直接升级换一对老的670用的Triad变压器声音可能更670些