The two new home cinema amps follow in the footsteps of the entry-level TX-SR343 and TX-NR545.
Onkyo is pushing the amps' support for next-gen surround sound formats, with DTS:X also incorporating Neural:X, which promises to use spatial mapping to bring a similarly all-encompassing sound to soundtracks encoded in other formats, such as DTS and PCM.
Each amp has eight 4K/60 Hz-ready HDMI 2.0a inputs and two multi-zone outputs, including HDCP 2.2-compliant terminals to support 4K streaming and even UltraHD Blu-ray discs, which are due later this year. High Dynamic Range (HDR) colour and 21:9 cinema-aspect are also supported.
Both the new Onkyo AV receivers support wireless streaming over Wi-Fi, AirPlay and Bluetooth, and integrate Spotify Connect. Onkyo’s Remote App 3 can also stream digital music stored on you mobile and brings access to various Internet radio and on-demand music services.
If high-res audio is your bag, then 192kbps/24-bit FLAC and DSD files are supported over DLNA, or you can ride the vinyl revival by plugging in a turntable via the phono input.
The TX-NR646 claims 160 watts of power per channel, while the TX-NR747 claims 175 watts and is THX Select 2 Plus certified. Both receivers are fitted with Dual 32-bit DSP Engines and a new 384 kHz/32-bit AK458 DAC.
Onkyo has also updated its AccuEQ room calibration with the aim of making the initial setup that much easier.
The new amps join home cinema amps from Denon and Marantz, which will also add DTS:X support to their existing Atmos spec later this year, albeit via a 199 euro hardware upgrade.
The Onkyo TX-NR646 will go on sale at the end of May, in black or silver, for £549. The TX-NR747 will be available in mid/end of June, in black or silver, for £849.