Although the RX-V640 is not as "powerful" as some other receivers in this price range, its discrete high-current amplifier design supplied enough power to respond quickly to dramatic changes in sound levels, providing a consistent output over long periods of time. Although the 640 lacks the convenience of an onscreen setup menu, the remote, along with the LED display on the 640 allows adjustment of all needed settings, including room size, speaker distance, and speaker levels. There is also a built-in test tone generator in the 640 that can be used to check the sound level of each speaker individually, or all speakers in a rotating sequence.
Another useful feature I was glad to see on the RX-V640 (which is becoming common on AV receivers) is the second zone opton. This allows setup of an additional two-channel amplifier and speakers, using the RX-V640 to send a line-level signal from one of its connected audio components. The source can be the same or different from what is playing on the main system. Video switching is not included in the second zone option.
A very practical feature, the Center Channel Equalizer, also deserves a mention. This function enables the user to match the characteristics of the center channel speaker to the left and right main speakers and also helps to enhance soft center dialog tracks that plague some DVD material.
The only "negatives" of RX-V640 I found were:
No direct phono/turntable input (vinyl is on the upsurge -- even with some younger folks -- more vinyl was sold last year than SACD and DVD-Audio discs combined!).
Only one coaxial digital audio input (one more would have been nice).
No onscreen display (It is nice not to have to turn on your TV every time you need to change settings -- but it is nice to have that additional option).
Although I personally would have liked to have seen these features, they, in no way, detracted from the audio or video performance of the unit itself.
With its moderate price, and loads of features, the RX-V640 represents an excellent value in an AV receiver in its price class. To recap: although not as powerful as some other units in its price class, the RX-V640, none-the-less delivers exceptional sound, which should serve well in most average sized rooms. The features of note were: Video Conversion, which allows mixing of S-video and composite video inputs and outputs; Second Zone pre-outs, which allow the user to supply either a simultaneous or second source to another room (additional amplifier required) and the Center Channel Equalizer, which is great for fine tuning movie dialog tracks. In conclusion, if you are considering either an upgrade from an old pro-logic receiver or starting a system from scratch, and are on a budget, consider the Yamaha RX-V640. I am giving it 4 out of 5 stars.
