MP 301 as poweramp?

Hi there,
I have spent quite some time reading stuff on this forum. Now I’m entering next step and join the party a bit further.

I have a problem I’m sure some of you can help me with. I’m building a 3way speaker. I would like to do a Bi-amp setup and use my old updated HK 680 integrated amp for the bass driver (below 400hz, passive crossover) and plan to use a Musical Paradise MP 301mk3 for Mid/tweeter (400hz and up).
Problem is how to make this work since MP 301 is integrated as well.

Can I simply take Pre-out signal from HK 680 and connect to line-in on MP 301 ?
I fear that setting volume knob on MP301 at 100% will start hum, heat and so on. If this is a bad idea, is it possible to find connexion point to be able to use MP 301 as a poweramp only? If this also is a bad idea, what similar tube poweramps could you recommend ? About same price and powerrange.
It would be nice to start the ”tube rolling” journey.

I’m hoping to use a powerful (John Wright) TL bass in combination with the magic of Tubes for mid and top ;)

sounds like a good plan to me :). If you turn the MP301 up all the way then it becomes a power amp with volume controlled elsewhere. You'll have to check on your HK to see if the pre out is fixed level or adjustable level (most likely adjustable). If it's adjustable then you are good to go. You might have to use that extra instrument, your ears, to see if you need to dial back on the MP301. My oracle sees a wonderful future in your sound set up :)