I am still using an older BASH 300w plate amp on my main floor DIY 12 inch sub. Good unit.
I am still using a 500w Dayton plate amp on my basement HT DIY 2x12 inch sub. Good unit.
I bought one of those Crown XLS1500's with an eye on using it as a sub amp, but frankly it is very good acting as my main 2 channel amp. If I ever go tubes again, I will repurpose the 1500. It is a workhorse, and it sounds good.