While I can understand your hesitation after this whole fiasco, do know that as a whole, SVS equipment is generally regarded as being VERY reliable. Their amps and drivers are very well made and most people have no issues. It does make you wonder if something happened in transit. They are very heavy, so wouldn't be surprised if a package handler dropped them. Even if no damage was evident, and they are very well packed by SVS, I suppose it's still possible. Still crazy you ended up with TWO bad amps. Also, just so you know, SVS bench tests EVERY subwoofer at their facility in Ohio before they leave, so I can just about guarantee it left their shop in working order. There's good reason they have the best warranty in the business.
Also possible: Maybe they got nailed with a power surge? Are they protected? Maybe they weren't but your other gear was? I don't know. Just spitballing ideas at this point.
Either way, I really want your selection of new subs to work out for you. I'll admit, I'm biased as I am a dealer, but that's also why I believe the brand is so good as a whole. Anyhow, do what you gotta do, but it'd be awesome if you got the problem resolved before moving on all together. Just my $0.02.
Just odd of two power amp failure.
I would have given them another shot. The PB13 have a significant advantage over the VTF-15H under 35hz which was I thought you were chasing. For example the PB13 extends to 12.5hz at 89db and at 16hz has about a 10db advantage over the HSU and 5db at 20hz, that is huge...if you are not chasing lower frequencies then go for the PSA V1811. They will be easier to integrate.
And that from a guy (you), meaning not bias, since you own PSA.
Room interaction problem?