Surround setup problem

In preparation for a surround setup I connected HDMI from an Ayre DX-5 DSD disc player to a Bryston SP3 processor, with front LR to the by-pass input of an Ayre KX-5/20 preamp.  The plan was to use the KX-5/20 and VX-5/20 amp for front LR with NAD digital amps for side and rear surround.  The setup resulted in audio dropouts with about a 50% duty cycle and noise before each dropout.  Disconnecting the HDMI from the SP3 eliminated the dropouts even though the by-pass between the SP3 and preamp was still connected, but that also eliminates surround.

I may end up using a spare NAD M22 for front LR with a switch to select it for surround or the VX-5/20 for stereo.  Any recommendations for such a switch?

db