8-10k budget suggestions please

I hope I am wrong for the sake of your excitement, but a Krell amp is one of the last amps I would have paired with B&W. I know most of them to be very forward and analytical, and you needed something to tame the same characteristics of your speakers. Try not to let the, "new smell"  of the amp cloud your ability to listen critically once the pairing is made...

Krell will have no problem driving those speakers. Will sound great! Good source like a Denafrips DAC would be next. I like B&W speakers, but they are very unforgiving of your source. I’m a huge believer in empirical numbers and data… They are very important and a good guide, but somethings numbers just can’t measure. The most powerful audio processor ever made is between your ears. No oscilloscope, multi meter or analytical software can come close to measuring what’s going on there. I love the audio science review guys, but the best topping DAC just can’t compare with my terminator. tried one and sent it back. If you ever get the upgrade bug or tire of your current system, consider an SET as mentioned above before you start blowing big bucks. Enjoy!

… Also, don’t be afraid of a little bit of digital EQ through Roon or such.
Quick and dirty. Download an audio analyzer app on your phone. Set your speakers up. (Do a little research on speaker placement and tow in). Stream some pink noise through the system. From seating position look for any obvious frequency peaks/dips on your app. Adjust toe in and placing to smooth. Then, smooth remaining peaks with digital EQ. Don’t try for completely flat, no more than -2 to-3dB digital EQ. Don’t try to flatten every little tiny peak you see. Leave them alone. Just the big ones. Less is more. I would leave dips alone with EQ. Instead, fine-tune the placement. Don’t get too uptight about it though. Adjust and fine-tune focus and staging by ear. Moving your seat back-and-forth just a few inches can have a dramatic effect. You could also experiment with one speaker at a time measuring a meter away. And then at seating position. Just need to get in the ball park then let your brain adjust a few weeks and it will do the rest! Don’t stress over this crap too much. Have fun with it!

@laaudionut The new Duo XD amps are warm and very smooth.

@asmithkash My Krell K-300i integrated drove a difficult to drive Thiel CS3.7 nicely, not all the amps I tried it with drove them well. The Thiel should be more difficult to drive than the B&W.

Transparent cables are what I use with my Lumin/Gryphon/804 system. My 804s are the latest version and measure comparatively poorly AND present a tougher load to the amplifier than your 804s, yet they were my choice for my tastes/room/budget etc. Auditioned lots of other speakers like Sonus Faber Totem Focal Spendor etc. Don't let other people tell you that your 804s are going to be a weak link, there are too many people in the hobby who love to tell others what kind of sonic profile is ideal. That Krell is going to be a fantastic match for your 804s, and yes buy good cables, and a good power conditioner (I use a Puritan PSM156), clean power is a must if you want the best out of all the upgrading you're doing.