I’ve got Emotiva XPR-1 amps, which also use the rare 20A IEC (C19) connector. I don’t know if Krell does anything special with their power cords, but I’m going to assume it’s a generic 12awg or 10awg cord (nothing special like OCC or exotic types). The only company I’ve seen that had an option to put 20A IEC connectors on their cords are Audio Sensibility. Google for their website. They are in Canada, so the prices are CAN currency. He ships to US locations using USPS Priority Male and I can state that the guy is very reputable. I have bought many things from him.
Alternatively, you can re-terminate your Krell power cord with different IEC/Male connectors (or build or your own using your preferred A/C wire). The only choices you have is Wattgate or Furutech, depending on what kind of sound you are looking for. DO NOT buy the Wattgate EVO connectors. They use hex-head set screws and are a pain to work with.
Wattgate Classic standard (brass) - these are very fast/clean sounding, but I have found them too forward/strong/solid-state/sterile for my tastes. I would say to use the brass connectors if you have a very laid-back preamp/source you are trying to compensate for (such as tubes or other). Otherwise, it may be too strong/solid-state sounding for you.
Wattgate Classic gold/silver - I have not tried either of these, but the silver-plated option is nice if you like the "silver" sound. It may be weaker on the bass/mid-bass frequencies. The gold-plated may help calm down the brass signature of Wattgate.
Furutech gold-plated - Excellent if you want a more laid-back warm sonic signature, but still has excellent resolution. This can be too laid back and lacking in detail or "separation of instruments" in some cases. The bass is strong and full, but not as tight/punchy/deep as rhodium below.
Furutech rhodium-plated - Excellent resolution. very fast with good strong/tight/deep bass. Mids and highs are excellent resolution. In my opinion, these are the best connectors. However, they are very transparent and could reveal problems in other areas of the system. I have found if you go down this road, you may need to replace every power connector / fuse / interconnect with rhodium-plated to get all the way. But it is absolutely outstanding when you get there.