@ronwave
You will drastically change the sound you say you enjoy so much by going from Class D SS to Class A tube. I'd be surprised if using the Nova500 would provide a magical pairing when using it only as a preamp to the tubes. I'd definitely buy your tube amp used so you can sell close to break even if you decide the synergy isn't great. You're just tinkering to see what other sonic signatures are all about and there is nothing wrong with that but it doesn't sound like you're being very deliberate to try to see what tube magic is all about by cobbling together new and existing components that are just handy for you.
Regardless, the system sounds very good and I enjoy it. However I am very curious about class A/tube amps.
You will drastically change the sound you say you enjoy so much by going from Class D SS to Class A tube. I'd be surprised if using the Nova500 would provide a magical pairing when using it only as a preamp to the tubes. I'd definitely buy your tube amp used so you can sell close to break even if you decide the synergy isn't great. You're just tinkering to see what other sonic signatures are all about and there is nothing wrong with that but it doesn't sound like you're being very deliberate to try to see what tube magic is all about by cobbling together new and existing components that are just handy for you.