surround processor?

A good option would be to get a used Classe Sigma SSP MKii (if you can find one as they are out of production). The 2 channel function is based on the highly rated Classe CP 800 preamp. There are probably better options if your focus is 7.1, but it performs well enough and the 2 channel is very good through the USB input or analog XLR. I use a Lumin streamer and connect it via analog XLR with the Sigma in bypass mode.

Agree with Vinylshadow on the Classe SSP 800.  The Classe Sigma SSP, that I have, was a newer, and less expensive model when it came out. However, it also has a great DAC for 2 channel.  The SSP 800 is a better choice if you prioritize multi channel as all channels are fully balanced, while the Sigma is only fully balanced for 2 channel.