AV preamps and receivers have become overly complicated affairs, offering up features and connectivity that would've been science fiction twenty-five years ago. Meanwhile, two-channel preamps have been left largely in the dust, performing much as they have for the past century. With the proliferation of digital music, especially iTunes and other downloadable music files, two-channel DACs (digital to analog converters) have experienced a resurgence, but two-channel preamps have remained the same - until now. Enter Classe's newest two-channel preamp, the CP-800 stereo preamp processor, a $5,000 no holds barred two-channel preamp that packs a few bells and whistles normally reserved for its AV counterparts. Could the CP-800 be the first in the evolution of the stereo preamplifier? That's what I wanted to find out.
• Read more stereo preamp reviews written by the staff Home Theater Review.
• Learn more about The Evolution of the Two-channel Preamp.
• Find a pair of Bookshelf Speakers or Floorstanding Speakers to pair with the CP-800.
The CP-800 replaces both the CP-500 and CP-700 preamps from Classe. From the front, it doesn't look all that different. The CP-800 is clad in Classe's now-trademark white façade with black accents surrounding its touch-screen controls and large volume knob. The CP-800's edges round delicately towards the rear of the unit, giving it a modern architectural flair that is unlike anything you'll see elsewhere in high-end audio. The CP-800 is nearly five inches tall and 17.5 inches square, tipping the scales a solid but not unruly 23 pounds.
The front of the CP-800 sports a traditional headphone jack as well as a USB input, both of which rest between the left-mounted touch-screen and right-positioned volume knob. The touch-screen is a two-color affair, but the CP-800's screen has traded black for blue and left the white alone. While the combination of white on blue may seem odd or, worse, difficult to read, rest assured, it's not - in fact, it's quite pleasing and easily read from some distance (12 feet for me).
As futuristic as a touch-screen may be, it's when you focus your attention on the CP-800's rear panel that things begin to really take shape. Moving left to right, the first things you'll notice are the CP-800's master power switch and detachable AC power cord, next to which rest its nine digital inputs. Wait, what? That's right, the CP-800 has nine digital inputs: four optical, three coaxial, one AES/EBU and a second USB. All nine digital inputs feed the CP-800's all-new DAC, which when used with either of its two USB inputs will provide more than just your average run of the mill conversion. More on this in a moment. To the right of the CP-800's digital inputs are its various IR, trigger and control ports, which include RS-232 and Ethernet (forthcoming), among the other more traditional 12-volt varieties. Along the bottom, again moving left to right, are the CP-800's five analog audio inputs, three unbalanced and two balanced, all of which are assignable by the user. To the right of its analog inputs are the CP-800's five analog outputs, both unbalanced and balanced, which, like its analog inputs, are all user-configurable. How user-configurable? The CP-800 can accommodate multiple subwoofers as well, or multiple amplifiers in a bi-amp configuration, or both, making it the ideal preamp for those who enjoy full-range two-channel playback, as well as the occasional DVD or Blu-ray disc.
Under the hood, there are a number of major advancements unique to the CP-800 and to Classe. First there's the CP-800's Switch Mode Power Supply (SMPS), which is smaller and more efficient than conventional power supplies. The SMPS inside the CP-800 has four separate outputs: one for left and right audio circuits, one for the digital circuits and one for the USB system, which allows for connected USB devices to charge while plugged in.
Speaking of USB, the CP-800 is an Apple-certified device. Its front-mounted USB input enables not only full playback of Apple music files, but also charging capabilities. The included CP-800 remote can also access and provide simple transport control of any Apple-attached device, thanks to the 800's Apple authentication chipset. Connecting your home computer to the CP-800's rear USB port also allows for the proper playback of music files from any player. Taking things a step beyond mere Apple certification, the CP-800's USB performance is further enhanced by the isolation of the USB circuit itself. The CP-800 also employs what is referred to as an asynchronous USB DAC, whereby the jitter-induced by one's computer or portable digital device is effectively removed by not having the source be responsible for the clocking of the incoming signal. This ensures not only a more accurate and natural portrayal of the digital signal, but also reduces noise - another byproduct of both the CP-800's asynchronous DAC and USB circuitry isolation. The CP-800 uses what is called a Field Programmable Gate Array (FPGA) located close to the DACs and master clock that essentially takes the incoming signal and buffers it before sending it along to the 800's master clock, which is synchronous to the internal DAC. Either of the CP-800's two USB inputs can take advantage of the new asynchronous DAC setup.
Beyond its built-in DAC capabilities, the CP-800 also features pretty robust tone controls, as well as bass management and parametric EQ. Since most users will undoubtedly connect their various source components to the CP-800 via some form of digital connection, the tone and EQ controls are able to be tackled in the digital domain. Furthermore, because so much of the CP-800's abilities are dealt with in the digital realm, it keeps the internal signal path short, thus preserving more of the signal, rather than passing it along through a bevy of third-party components or cables.
This brings us to the CP-800's remote, which I feel also doubles as its theft deterrent stick, as it is forged out of aluminum and weighs more than any remote I've encountered. The remote is fully backlit, feels good in hand and is easy to use, though for initial setup, you or your Classe dealer will most likely use the CP-800's touch-screen.
Unboxing the CP-800 and placing it in one's rack is easy enough. Making the requisite connections is equally pedestrian, which my case involved connecting my Cambridge Audio Azur 751BD Blu-ray player to the CP-800 via an optical and coaxial digital cable, both of which were generic in make. I ran a separate set of Transparent Cable analog interconnects from the 751BD's stereo analog outs to the CP-800's analog inputs in order to test its analog performance. To test the CP-800's USB capabilities, I used my iPhone as a transport playing a bevy of digital music files, ranging from 256K to uncompressed, which were sent to the Classe via Apple's own iPhone to USB cable that comes free with purchase.
I initially connected the CP-800 to my review sample Pass Labs X250.5 stereo amplifier. However, in order to test the 800's flexibility and bi-amp capabilities, I later substituted in my Parasound 5250 v2 multi-channel amplifier, with channels one and two powering the right speaker and channels four and five powering the left. As for speakers, I relied solely on my reference Bowers & Wilkins 800 Series Diamonds, which I connected to my amplifier via four runs of Transparent speaker cable.
I used my two JL Audio Fathom f110 subwoofers to augment the 800 Diamond's bottom end. Since I use an outboard parametric EQ for both subwoofers, transferring that information to the CP-800's internal parametric EQ was easy enough. However, my reference EQ setting uses seven filters, whereas the CP-800 limits you to only five. With some help from Room EQ Wizard, a free downloadable program, and Home Theater Equipment forum member RayJr., I was able to come up with a new curve that closely matched that of my reference, using only five filters. In a direct A/B comparison between my reference filter and the modified one used for the CP-800, the difference was negligible. Once I had the parametric EQ inside the CP-800 dialed in, it was simply a matter of telling the preamp which input was which, which EQ and bass management settings to apply to each, and identifying that the remaining two auxiliary outputs were to be used for amplification and not for additional subwoofers. In order to run two subwoofers and still have the requisite outputs for bi-amping, I had to run the subs as a summed mono pair, meaning they were fed the same signal, only split between the two. If you want to run true stereo subwoofers out of the CP-800, you can. However, it makes true bi-amping impossible.
From unboxing to final install, it took several days, due to a lot of experimentation and evaluation. However, you could easily have the CP-800 installed in your system in less than an hour if you were strictly attempting to utilize it in a plug-n-play configuration. That said, if you are a plug-n-play type of user, may I suggest you look elsewhere, for the CP-800 isn't going to be for you - it's a preamp for those who are willing to sit down and make sure everything in their system is operating to 11. Take the time to get everything just right and the CP-800 will reward you handsomely, though don't be surprised if, down the road, you discover a setting or configuration option you didn't notice or rejected at first but now find preferable. To quote my friend, "The CP-800 is a product you 'grow' into."
I honestly don't listen to a great deal of music via USB connected devices. However, I feel that in the future I will, so to become more accustomed to the sound, I started my evaluation of the CP-800 with its USB inputs. In order to properly compare and contrast the 800's USB capabilities with that of its other digital abilities, as well as its analog, I used a track that I was intimately familiar with, Diana Krall's "A Case of You" off her album Live in Paris (Umvd Labels). I used the CD itself to make several rips of the track, one at the iTunes standard 256K, one in Apple's own lossless compression and lastly the disc itself. I loaded the two MP3 files onto my iPhone and connected to the front USB input on the CP-800.
Read more about the performance of the Classe CP-800 on Page 2.