can any AVRs use USB instead of HDMI for multichannel?

[LuvMyQuad]

I think you misunderstand how it works. Yes, the data can flow both ways, but only one of the two controls the sending and receiving of the data, and that is the host. Like I said, computers, AVR and Blu-ray players are hosts and storage devices are devices. Have you managed to successfully connect your AVR to you computer with a USB cable? If so, I'd like to know which make and model of AVR offers this possibility. The only exception that I know of are phones which can act both as a device (plugged in you computer) and a host (connect a storage device or interface to the phone).

By the way, when you connect a storage device to a computer, AVR or Blu-ray player, you transfer files to it and the host controls the sending and receiving of the files. When you connect your computer to a USB device that is not a storage device, you communicate with the devices in their specific language, be it a scanner, printer, keyboard, mouse or audio interface. In the particular case of the audio interface, the host sends and receives an audio signal (usually in PCM format) over USB, not files.

I don't have an AVR. And now that I think about it, what you are saying makes some sense, but only with respect to AVRs

There are a multitude of stand alone DACs that have USB inputs. They are not for plugging storage devices into. If one plays back files via a media player (ex: Kodi, or Foobar) with the output specified as USB (using an ASIO driver) and feeds that to the DAC, the DAC will decode it and pass it along. Does this make the DAC the host?

 

[jimfisheye]

Don't assume anything follows standard protocol with this stuff! Read the manual and read the fine print. USB has capabilities and standards but the product designer can do what they please. Just like HDMI (both inputs and outputs) can have audio disabled. This stuff is used as copy protection and format competition often enough.

Meanwhile standard professional USB connecting audio interfaces DO tend to follow standards. These tend to be designed to deliver maximum bang for the buck in features and sound quality. AVR style consumer electronics are too often designed to hide things or disable competing formats. If some level of usability takes a hit along the way, that's tough.

Semantics and all...
Stand alone DACs have a digital audio input.
Audio interfaces that include DACs will have USB, firewire, thunderbolt, HDMI, or pci connection (sound card). (Always be suspicious of HDMI!) It's the audio interface part that connects to the computer. Think of an AVR as an audio interface, DACs, analog preamp, and power amps all in one box.

But like I said, read the manual before buying anything!