i am looking to replace my Krell with tube amps,

VTL 450 wpc and up. Wolcott is a good one too. Do you live in a warm climate? If so you may need A/C at least in the summer. I have a Callisto Partial Eclipse with two power supplies and it by itself heats up my room pretty quick. Although my room is smaller and is upstairs. I would like to try some high powered tube amps as well but don't have A/C at the moment.

I think you should wait till you get the Callisto to decide on amps. I also went from a Calypso to a Callisto and you are in for a treat. You may decide you do not need to switch amps.

I went from FPB 600s to ARC.
Depending on your budget, there is a wide variety to accommodate your needs and ARC tends to lean towards SS when it comes to bottom end control which is a real nice attribute.
I tried the VTL's as well and preferred the ARC based on the bigger model ARC I settled for. NO tubes will have that staggering control of what the Krells can provide but it was a compromise I was willing to take to fill the other avenues that the ARC provided. Good luck

Thanks for all your feedback,
Do any one have Ayon Orthos ii? Is much cheaper than Tenor for a demo set. Ayon Orthos ii is 250watts price about $18000 vs Tenor 175s probably around $33,000 demo. i am leaning towards Ayon. Will try one in Seattle store.

There are a pair of VTL sigfrieds for sale in Seattle on this site. Those would have plenty of power and sound fantastic. I have heard them powering a pair of Wilson Alexandia at a dealer some time ago and was very impressed. I'm not a fan of Wilsons but that combo was sweet.

I have no assosiation with the seller but suspect that it is the Dealer that I heard them at.

The VTL Sigfrieds are sweet if you have the dough. I'd have to second that option. Manley also puts out some pretty powerful tube amps that should be a bit cheaper.