McIntosh MC901

The McIntosh MC901 is a monoblock combining a 300-watt tube amplifier and a 600-watt solid-state amplifier for dedicated bi-amplification. Rather than asking one circuit to handle the entire loudspeaker, it assigns different frequency ranges to amplifier sections selected for their particular operating strengths.

In a properly configured system, the upper range can retain tube texture and natural decay while the low frequencies gain the grip and current capability of solid-state power. The important result is not contrast between the sections, but continuity through the crossover region and stable timing from top to bottom.

We would consider it for large bi-amp-capable loudspeakers where the upper ranges and bass section are best served by different amplifier topologies. Successful integration depends on the loudspeaker’s crossover access, impedance, sensitivity, and recommended bi-amplification method. The adjustable crossover controls should be set as part of the complete loudspeaker and room setup, not treated as tone controls.

This is for an owner who wants a purpose-built bi-amplified system without managing separate amplifier brands and external crossovers. It requires careful commissioning, but daily use is straightforward once established. Its long-term value comes from giving each section of the loudspeaker appropriate power while preserving one coherent musical presentation.