In my world a “good” power amplifier is one that can drive a wide variety of loudspeakers successfully without drawing undue attention to itself. The C-100S stereo power amplifier accomplished this goal easily. No matter which of my loudspeakers I tethered to the C-100S, they sounded like they should have sounded. I never had any sense that there was anything different happening to their harmonic balance as a result of the amplifier/speaker interface.
In spatial rendition and imaging the C-100S matched the dimensionality of my reference amplifier, the Pass X150.8. Whether it was my own two-channel live concert recordings or streaming sources from Tidal or Qobuz, the image placement, depth, and space between the instruments were preserved. The C-100S was also exceedingly quiet in terms of background noise within my desktop system. Regardless of which loudspeaker I employed, I couldn’t hear any hiss or hum even when my ears were only inches away from the drivers. At normal nearfield listening distances—approximately two feet from drivers to my ears—the system with the C-100S stereo power amp in place was dead quiet. As I indicated earlier, in my room-based system there was some hiss, but it was due to the long single-ended run, rather than the amplifier itself.
When it comes to power capabilities, although it delivers “only” 100 watts into 8 ohms, the C-100S had no issues driving the 91dB-sensitive Spatial X2 loudspeakers to more than adequate volume levels with plenty of additional travel left on my preamplifier’s volume knob. In my desktop setup, I found no need to boost the C-100S amp’s gain to 32dB because even 26dB of gain was more than sufficient. If you have inefficient loudspeakers with less than 84dB sensitivity you may want to investigate one of CIA’s more powerful amplifiers, but for anything above 90dB, the C-100S stereo power amplifier should do the job with ease.
Speaking of ease, the C-100S delivered all the music in a relaxed, natural way. I never got any sense of solid-state upper-frequency grain or grit. Also, I never heard any upper-midrange or lower-treble glare when the power amp was pushed by challenging material. In that way the C-100S amplifier reminded me of my favorite reference microphone preamplifier, the Grace Lunatec 3, which always retains its clean, clear, and controlled sound even when hammered by hard, fast transients. Like the Lunatec, the C-100S remained unruffled by even my most dynamic live recordings.
For some audiophiles the highest praise that can be heaped upon a discrete solid-state or Class D amplifier is that is sounds “tube-like.” My position is different. I prefer a power amplifier that attempts to sound as invisible as possible—a straight wire with gain, to repeat that old audio cliché. The C-100S stereo amp provided more than enough power to drive all the loudspeakers I threw at it and did so in a way that allowed each loudspeaker’s unique personality to come to the fore. I suppose if you want an amplifier that has “personality” you should look elsewhere. But if you need a harmonically neutral power amplifier that you can attach to a wide variety of loudspeakers, the C-100S would be an excellent choice. And priced at $1500, the C-100S stereo power amplifier ranks as a “best buy” in my world.
Specs & Pricing
Power output: 180Wpc into 4 ohms, both channels driven; 100Wpc into 8 ohms
THD + Noise: <.006% (1 watt/1kHz)
Input impedance: 100k ohms (Teflon-insulated RCA jacks)
Output impedance: 0.015 ohms (5-way binding posts)
Voltage gain: 26dB/32dB (user-selectable via external DIP switches)
Input sensitivity: 1.4V/26dB, 0.7V/32dB
Maximum output current: 14A (per channel)
Power consumption: <15w (idle)/90% efficient @ rated power
Dimensions: 8.5" x 2.75" x 10" (including binding posts, etc.)
Weight: 6 lbs. (9 lbs. shipping weight)
CHANNEL ISLANDS AUDIO
567 W. Channel Islands Blvd.
Port Hueneme, CA 93041