Krell KRC preamp question?

Can anyone tell me what the differences are between the KRC, KRC2, and KRC3 preamps? I need a back up and have decided to go with one of these. Thanks for any help.
I hope I remember correctly.

In order of quality:

KRC3 - best

The KRC-HR betters all of the above.

Thanks Richard. I guess i will try to get either the KRC3 or HR model. I have also heard the KCT is a little warmer sounding but less transparent than the KRC models. Does anyone have any opinions on this? My Krell amps (FPB-650M) do not use cast so this is not a requirement.
The information from Drrdiamond is incorrect, the Krc was their top of the line, it was replaced by the Krc-hr, both models are superior to the Krc3 or 2.
Can you give give me any sonic differences between the KRC and KRC-hr models. Also any info on how these two compare with the newer KCT preamp? (will not be using cast cables)

As you can guess the KRC2 is at the bottom of the list.

There is a debate about the KRC-3 and KRC, some like the KRC-3 and others the KRC. Depends on taste, although officially the KRC should be better. The HR is better but whether it is worth the money difference (should be less difference used)is another question.

A question: Would a modern Audio Research SP16L see it off?
It is ver difficult to explain the sonic differences, I preferred the KRC-HR, to me it sounded sweeter and more natural, of course this is only my taste and yours may be different.How it compares to the newer KCT I have no idea as I have never compared the two. I suggest you try to audition these preamps and make your own decision. Most of the suggestions seems to be based on what should sound better because of price or based on reviews which people have read, not on personel experience with the products, which is the only opinion that really is valid.
I own the KCT & the KRC2. The KRC3 is at the bottom of the list. Not the KRC2 as noted above. The difference of sound between my KRC2 & KCT is miniscule even when using the CAST cables. The KRC3 has less inputs & features. I changed to the KCT basically because it matches my FPB300cx amp visually. The KCT does have more cool features though. I have swapped out the cables between CAST & balanced for listening tests on the KCT. Very close to my ears.
You can propably go the Krell web site and download the owners manuals. Then you can compare yourself.
Disclaimer; I had a KRC2 for sale here on Agon. It is sold waiting receipt of funds, so I have no vested interest in pimping its quality.
Enjoy, John
My above list above is based on my personal observations (listening), a dealer and custom installer, and Krell themselves as I have a great relationship with one of their major employees.

I have never heard before that the KRC2 was NOT at the bottom of the list. The reason some feel that the KRC3 is at the top of that list is that it has many advances that are actually used in the KCT.

To me, the the KRC sounded the same as my old KBL, but with remote capabilities. The KRC-HR was a definite improvement, primarily in transparency. I ended up getting the HR.

I could not afford the KCT and since my system is actively biamped, I cannot use the cast technology between preamp and amp. My dealer friend did upgrade his personal system to the KCT, but felt that the HR was more exciting, and he was ambivalent about whether he made the best choice.
The Krell KRC-HR and KRC can't sound different because they are identical piece
HR is only to be able to connect your theater-throughput thru the input S4
if you don't use your A/V surround system you will no need that feature

Here is a copy from the manual about the only difference

The $4 input of the KRC-HR can be set to operate as a unity gain stage. This
removes the KRC-HR volume control from the signal path. Volume control is
then transferred from the KRC-HR to an A/V surround processor connected to
the $4 input. This feature greatly simplifies the installation of a surroundsound
processor into a high performance audio/video surround system.
If the Theater-Throughput option is activated, select S-4 when your home
theater/surround system will be used. In this mode, all control of volume is
performed by the A/V surround processor connected to that input. Specifically,
Level, Balance and Gain are disabled on the KRC-HR for the S-4 input only
when the Theater-Throughput is engaged. Mute and Tape (monitor input) will
function normally.