The manufacturer offers an upgrade service ( 280 €) in which sound-determining components are replaced with new ones (if necessary). In any case, new power supply electrolytic capacitors from Panasonic , lower-induction emitter resistors, fresh end transistors are used. Instead of Sank 2SC2837 and 2SA1294, the same types are used by the Sino-Indian company ISC.
A new circuit with a very high-quality National Audio IC in the input stage has been used since mid-2010. Previously, this was an Ic of type AD 797. The previous hedgehogs cannot be upgraded to this level by an upgrade!
The preliminary stage "beta" also belongs to this series.