Wow 8x15 meters? That’s about 26x50’ if my math is correct.

What flavor 604 do you have? I don’t think they’ll have an issue filling the space, but you might need more than 10 watts. I would give them more power.

It also depends on how loud you listen. I push my 604G’s pretty hard. I power them with a 250wpc amp.

But a pair of A5/A7’s and a couple 18” subs would sound good also