Having had an opportunity to test Denon AVR-S640H vs Pioneer SC-LX501, I’d like to share my impression here to facilitate your choice of a new AV receiver.
The number of channels for receivers is different - 5.2 versus 7.2, respectively, for devices. In terms of power, there are differences, the AVR-S640H has such a ratio W/Ohm - 75/8 20Hz-20KHz, 100/6 1KHz, while the SC-LX501 has a power of 120/8 20Hz-20KHz, 180/6 1KHz. A common feature for devices is the same total harmonic distortion - 0.08%.
The manufacturer installed different DACs, the AVR-S640H received the model 192 KHz/32-bit, but the SC-LX501 is equipped with AK4458 384 KHz/32-bit. The Bi-amping function is implemented only in the Pioneer SC-LX501. Both Denon AVR-S640H and Pioneer SC-LX501 can transmit an audio signal directly to the amplifier and bypasses any DSP processing. Each of the receivers has a Bluetooth connector. The contenders have differences in the supported services from Apple - AirPlay, AirPlay 2 versus AirPlay respectively. Access to the Spotify service is on each of the competitors. The number of available streaming services varies for receivers, the Denon AVR-S640H works with Deezer, TIDAL, Pandora, Napster, SiriusXM, TuneIn Radio, iHeart Radio, Sound Cloud, but the Pioneer SC-LX501 works with Deezer, TIDAL, Pandora, TuneIn Radio.
Support for the HDR function can only boast of each of the AV receivers. The quality of 4K 60p signal remains unchanged when transmitting from a source to a TV or projector via HDMI for both receivers. Signaling over HDMI in standby mode can provide the AVR-S640H and the SC-LX501. Video scaling is only possible with the SC-LX501. Each of the participants of the comparison has a Dolby Vision.
The number of HDMI inputs/outputs varies depending on the receiver, the AVR-S640H has 5/1, and the SC-LX501 has 7/2. HDMI Audio Return Channel is implemented in both devices. HDMI eARC is not supported by the AVR-S640H and the SC-LX501. When comparing receivers, it becomes clear that each of the rivals can work with HDMI CEC. AVR-S640H and SC-LX501 support the standard HDCP 2.2. Like most receivers, our models have a built-in phono stage for connecting a vinyl player. There is an ECO mode in AVR-S640H. The Denon AVR-S640H and the Pioneer SC-LX501 can be properly configured using the setup assistant.
A Dolby Atmos multichannel audio format is available only in the SC-LX501. Only in the SC-LX501 realized a DTS:X surround technology.
The Pioneer SC-LX501 is better receiver in this comparison. Check Pioneer SC-LX501 price