The M99 is rather more exotic internally than the term “Class D” might suggest. SPEC uses an analogue PWM front end feeding a MOSFET Class-D power stage, together with an R-core mains transformer. The transformer and other major sections are separately shielded, while the inside of the chassis receives an EMC coating to reduce electromagnetic interference.

It uses SPEC/Nichicon HIBIKI-ICHI capacitors, developed specifically to achieve rapid response while retaining natural tonal characteristics. The design also uses carefully selected paper/oil and other capacitors in the power supply and output-filter sections.

One of the M99’s most unusual features is its mechanical construction. A solid spruce soundboard runs across the underside of the chassis—the same family of wood traditionally used in violin construction. This is supported by maple feet with hickory centres. SPEC deliberately uses the mechanical resonance characteristics of these materials as part of the amplifier’s voicing.

It can also be configured for power-amplifier operation, bypassing the normal volume-control function, which makes it potentially useful with a separate preamplifier. The optional RSR-1 remote receiver is external rather than building additional RF/IR electronics into the amplifier chassis.

Position in the range

The RSA-M99 sits very high in SPEC’s integrated-amplifier hierarchy. SPEC describes it as having a rich, mellow and highly musical presentation.