I currently run a Peachtree, but it is an older model ....
Certain older class D amplifiers utilized class D modules which were designed such that both the + and - speaker-level outputs are offset from ground by a large DC voltage. Something like 24 VDC if I recall correctly. And I’m fairly certain that some older Peachtree designs utilized those modules.
While a large DC offset on both the + and - outputs won’t bother a passive speaker, powered subs should not be connected to the outputs of such amplifiers without a special adapter which inserts capacitors in series to block the DC. And it may be hard to find such adapters, as class D designs produced in recent years no longer have those offsets.
Depending on the designs of your particular subs it seems conceivable to me that the symptoms you have described could be the result of connecting them to such outputs without a suitable adapter.
My suggestion is that you contact Peachtree and ask them if what I have described applies to the specific amplifier model you are using. If so, the alternatives are to connect at line-level, or to try to find the kind of adapter I described, or to make such an adapter yourself.
Good luck. Regards,