i am looking to replace my Krell with tube amps,

BAT may be worth exploring. I heard King V2 driven by VK-150 to good effect

Audio Research....but ya might wanna keep the Krell. Should have picked up a KCT preamp...tube sound without the tubes!

Have you considered having your Krell rebuilt.  I just had that done in November and for a whole lot less than the cost of a new amp, I had Krell rebuild my 30+ year of KSA-80B.  Its just marvelous.  So musical.  They put new caps in in and a few other parts, adjusted the bias and tuned it up.  It have never been serviced before.  And with Krell, two things you can count on, they will drive low impedances (mine is one ohm) and they early ones do sound nice.   If you have had yours 10 years, they probably sounded good to you, but could use some new HQ components.

Bailyhill

Be careful buying VTL used, they treat "used amps" different than those purchased new from a dealer.

Warranty if any is void and depending on age repairs can easily get cost prohibitive

Tubes are more fun, make music sound like it's supposed to, and make you a better person. Also, note how many non tube amps claim to have "tube-like" sound, which means, generally, they don't.