In July I scrapped the Boom system on my 2017 CVO Limited for a BT 4250 with BT Pro's in the fairing and Hertz SV's in the lowers. Awesome!.... but the wife said she kinda' missed her rear speakers.
Added a Soundigital 250.2D to each BT speaker bracket. One feeding a pair of Polk MM652's in the TP pods and the other to another pair of the 652's in Matazu bag lids.
Chose the Arc PSM (from authorized dealer) to optimize the 3 speaker types. Even with the stock tune I was all smiles; until I shut it down and got a couple of loud pops. Figured I could fix that with some delay added but never got the chance. The inline 3 watt fuse had blown and new fuses blow immediately. Wired per instructions; yellow (positive) and black (negative) direct to battery and red to accessory.
CRAP! Anybody have a phone number for tech support? Did not see it listed on the ARC website.

 

https://www.arcaudio.com/contact-us

Tech support is very helpful at ARC

 

I feel your pain with those pops dude. Some head units emit a small DC pulse through the outputs when they shut down or power on. Mine was bad enough to where I installed a PAC SNI-1 ground loop isolator on each set of preamp outputs and the pops were gone. Just for grins I tried plugging the RCA outputs from my head unit into the PSM when I got it just to see if it was my amp that was picky. Nope, POP. Fortunately it didn't fry anything but it was hideously loud.

That's the thing about these DSPs, they are similar to what audio gurus call a "preamp". I remember watching a video on YouTube from an engineer that built his own successful audio manufacturing company. He always said "there is no preamp like NO preamp". His reasoning being anything you put in the signal path will introduce noise. He said after some friends showed him what a preamp could do to make the sound warmer he started understanding more why folks like them, but they do introduce more things into the signal path than what they are fed. I fed mine a pop and it turned it into a bang.