As the co-designer of the Raven, but also a big fan of multichannel sound (going back to the invention of the Shadow Vector quadraphonic decoder in 1973), I’d advise simply getting the PS Audio preamp repaired. (Yes, we could make a 5.1 version of the Raven, but the market would be very small.)
The clicks are coming from DC leakage in part of the audio circuit. Any time there is any DC on a switch or volume pot, you’ll get crackles or pops and bangs. In fact, that’s about the only thing that will produce those symptoms. So, a cap has gotten leaky or a power supply has failed, which should be easy to find by a qualified tech who knows the circuit. Thus, PS Audio, who should know what’s inside their own preamp.
To the best of my knowledge, PS Audio does not publish schematics (very few high-end manufacturers do). You do not want to pay (by the hour) for a tech to guess what the circuit is by tracing the wires and circuit board layout. You want a factory authorized repair station that has direct access to the original schematic, so they can quickly find the failed part and replace it. That will be far cheaper than getting an audiophile-grade multichannel preamp ... those things cost $10,000 or more, because the market is so small.
It is kind of annoying to pay such astronomical prices for a preamp with only a slightly better grade of op-amp, but again, when production runs are small, costs go up several times. Also, AV equipment has built-in licensing fees for Dolby Decoding, DTS, various auto-EQ systems, HDMI interfaces, etc. etc. These fees are prohibitive for small audiophile manufacturers, but average out for Denon, Marantz, Yamaha, et al.