601 mono-blocks, that’s supper over kill for K-horns. I would not bother trying to bi-amp with that much power available. Unless you're considering moving to low power amps then maybe splitting the mid-tweeter and bass would help. That said if you’re not getting punchy bass from your K-horns I’d look at set up issue and speaker location room interaction first.
From my experience with Klipsch speakers (LaScala’s in my case) you’re better off with lower power amps, you are never using more than a few watts at best with 105bd speakers. I ran mine on 2.5watt SETs, 8wpc SET’s and some really nice 25wpc SS class A amps, and it was glorious. 600wpc is so over kill you’re barely getting that amp out of idle no reason to add more power IMO.
Subwoofers are hard to match to K-Horns but it’s possible with good quality sealed units. I would think that’s a better direction if you wanted more bass, after you address any set up issues and room interactions. You do have them in corners, right?