McIntosh C2200 Tube Preamp with Krell?

I have a decent combination Home Theater / Audio system, but have never had a dedicated preamp within it. The Krell HTS 7.1 has served as both my HT processor and preamp. Anyway, I'm strongly considering adding a preamp and thought a Tube preamp may be a good combination with my Krell. Below are my associated components - any help you can offer would be great. My three key questions are:

1. Would adding a preamp for audio be a significant upgrade over the Krell HTS 7.1?

2. Would a Tube preamp be a good match within my system?

3. If I go Tube - which one? I've been considering the McIntosh C2200, Sonic Frontiers Line 3, Conrad and Johnson 17S - Are there others I should consider?

Thanks for the Help in advance!

Krell HTS 7.1 - HT Processor
Krell 300cx FPB - 2 channel amp
Krell KAV 250(3) - 3 channel amp
Wadia 850 - CD
Shunyata Hydra - PC
Richard Gray 400S - PC
B&W Nautilus -HTM1 Center Speaker
B&W Nautilus -802 - Main Speakers
B&W Nautilus -805 - Rear Speakers
Cardas Golden Cross - Cables / Interconnects
I've owned many of the components you mention and have done a similar exercise.... So to answer your question, it all depends on the type of sound you like. When you add a good preamp in place of your HTS, you will immediately notice LESS BASS. I don't care what tube preamp you buy, they will not have the bass of your Krell. This may come to you as a big surprise and this may a relief. When I first compared to a tube preamp, it took me a while to really understand that the bass put out by the Krell was not necessarily "realistic" in terms of small scale music pieces because I was so focused on the fact that 10 to 20 percent of the bass impact was simply gone that I was unable to see it rationally.

With a tube preamp, the highs will become more liquid - wet sounding. More alive and less electronic and piercing. Easier to listen to and will simply envelop you vs. going right through you.

I ended up buying a Supratek preamp before I even A/B tested it against anything else out there. Yes.. I had owned other top brand preamps but the talk was so overwhelming about the Supratek that I just jumped in an purchased one for 2100 (new). I have posted elsewhere on this site about the comparisons I made between Supratek and CJ (16LS and ART) and the results were astonishing. I know people with $10,000 ---> $15,000 preamps who have switched to Supratek and say it transformed their systems to a degree they could not have possibly imagined.

Even with the Supratek vs. the Krell, some bass will be missing but, you will have a pure and beautiful midrange, tender highs and realistic bass.
First of all the Mac 6200 is an integrated amp so why would a 2200 be hooked to it unless only the amp part was used? Maybe you are thinking of the 602 amp. The 2200 is the new version tube preamp and not to be mistaken with the original 22 or the reissue of that - if you do not need remote control the original 22 would be a great way to go - if you go to the comments on the 2200 are not real good. The CJ would probably give you a great match with your gear and give you a totally different sound than your current system - better I would say but you know how that goes.
Go with a Conrad Johnson Premier 17LS which is very dynamic, warm, sweet and big soundstage. I never listened to the Krell 7.1 but for sure you will like the 17LS. It drives any amp ( I have a SimAudio W5, a good match ) and has a bypass connection from stereo to surround. I have also listened to McIntosh 2200 which is connected to McIntosh 6200 power amp. The sound is little dry and dynamic. Good luck!