This is the amp that started it all! The Custom 100 Head employs Partridge specification designed transformers. It is powered by 4xEL34 in the power stage, with 4xECC83 alternatively 3xECC83 and 1xECC81 in the pre-amp, giving a tighter sound. Switchable to 4, 8 & 16-ohm output impedance, the DR103 allows you to select from 100, 115, 230 and 240 volt sources. The dual channel pre-amp has high & low sensitivity inputs. Controls include: Normal volume, brilliance volume, bass, middle, treble, presence and master volume. Not much wonder the DR103 is included on many Top 10 lists of history-making amplifiers.