Channel Islands Audio, out of California, has been a favorite of mine since I bought their VDA-2 DAC, and an external power supply for my Squeezebox Touch. They are in the business of making handcrafted digital sources, Class D amplifiers, power supplies, and passive controllers for those who seek affordable components and great sound. CIAudio proves these two goals are not mutually exclusive.
I recently heard CIAudio’s excellent new USB to SPDIF converter and stand alone DAC, the Transient MKII, and was very impressed. After a conversation with Dusty Vawter, the owner and lead designer of CIAudio, in which I discussed my growing appreciation for passive “preamps”, he offered the $899 PLC-1 MKII Passive Controller for review. CIAudio also makes the $299 VPC-3 Passive. They differ dramatically in feature set. The PLC-1 MK II has multiple inputs, can be controlled via remote, and is roughly double the size.
Traditional “active” linestages, or preamplifiers, provide gain, volume attenuation, and input switching. They also match the impedance of the source and amplifier, and allow for the use of long cable runs. However, purists believe there are downsides. First, you have an additional gain stage that, with today’s standard sources, may be unnecessary. Next, there is an extra power supply on the line. And, finally, all active circuitry has its own sonic signature, regardless of any claims to the contrary.
Decent numbers of audiophiles have been using passive linestages for decades, but certainly, active preamps are the norm. I personally became interested passive units when I could not find any active linestages -- solid state or tube -- that were totally neutral. Many sounded superb, mind you, but were clearly colored in some way or the other. I decided it might be a good idea to let the amplifier provide the majority of the sonic colors, and let the source communicate with the amplifier with the most direct signal path possible.
Set Up & Listening
The PLC-1 Mk II features 4 RCA inputs, two outputs, and tape in/out, and a trigger for powering on or off components attached via a trigger cable. To use the remote control, you must plug the PLC-1 MKII into the supplied wal-wart power supply. This allows you to switch input, mute, power on/off an amplifier, and adjust the volume. Blue LED lights on the front panel indicate what input is selected. There is a solid, precise feeling volume knob on the right side of the front panel, and push buttons to manually select input or mute.
I was very impressed with the PLC-1 MKII’s build quality and appearance. Although not heavy, since it has no active circuitry or power supply, it nonetheless felt solid. As a matter of fact, all the CIAudio products I have had in my system have been well built. Internally, CIAudio says they use premium parts. According to product literature, "audio signals are switched by highest quality relays with gold-plated contacts, then fed to a custom ALPS® Blue Velvet motorized potentiometer. Circuit boards are 3 oz. copper with lead free plating, and assembled with lead-free silver solder for best conductivity."
The PLC-1 MK II was set up with Bryston BDA-1 and John Kenny Ciunas (review forthcoming) DAC sources, with Furutech and Stager interconnects. The PLC-1 MKII really got a workout driving no less than four separate amplifiers at various times. I used the solid state Burson Timekeeper, the EL84M tubed Bob Carver Black Magic, the KT120 tubed Audio Research VS55, and the new KT120 tubed Rogue ST 100 amp (review forthcoming). They were all connected to the PLC-1 MKII with Transparent MM2 Super interconnects.
Right out of the box, the PLC-1 MKII proved to be subjectively neutral, with less sound of its own then any active preamp I have had in my systems. Essentially, what I heard was the sound of the source and the amplifier driving the speakers. How did I determine this? With each of the four amplifiers I used, their unique sonic character was apparent. If the goal of a passive controller is to pass the signal through without editorializing, then that goal was met. Obviously the only way to determine if the PLC-1 MKII was totally transparent is to connect a source direct to a power amp -- and with no way to attenuate volume, a blown speaker is in your future. With the Carver amp, which does feature a volume pot, I was able to do this on a limited basis. But the Carver sounds its very best with the volume pot completely open, so comparisons were inconclusive. Nonetheless, to my ears, the PLC-1 MKII added little, if anything, sonically.