Guys, I'm designing a vacumm tube audio amplifier.
Configuration: push-pull ultralinear class B of EL34

But I need some opinions

.
In addition to the analog line entry, I would also like to put a couple of modules:
1) DAC composed of USB input, analogue line output.
2) Bluetooth audio receiver, always with line out.
Can you recommend ready-made and tested modules?

Can you also advise me on shielded relays for input selection? (old school method)

Thanks for the attention

This is the 3D model of amplifier: