Since Krell 302e & Cary SPL-05 have (gain/imp issues) what tube pre is best w/ the krell?

Looking SS enhanced sounstage,bass slam plus the warmth of tubes.

I would actually look at the Krell 202 or 222 preamps (even an older Krell KAV-280p is nice, but doesn't have the power supply of the 202/22).  The Krell's bipolar Class A gain circuits give you a nice sweet sound but still have the slam/punch/immediacy.  I would avoid the Krell Phantom preamp as I think they are overpriced and there's nothing much in them (even KAV-280p is better in my opinion).

You could look at some of the Pass Labs preamps.  They are Class A and use JFET/MOSFET gain circuits instead of bipolar.  This may give you more of a richness in the sound (not that Krell would be lacking warmth), but keep in mind that not all FET circuits are created equal.  I have not heard Pass Labs, so I could not comment.

Eric is a fan of Ayre, but I have no idea what that sounds like.

Thank you...Just spoke to some people about Pruma-Luna Dialog pre.
Or Prima-Luna pre and power amp.  Just not sure of how that would sound, and how they would drive Celestion A3 speakers, w/ are very power hungry.
BAT tube preamp with BAT ss amp. Big powerful sound i think your looking for.  
What gain/impedance issue? Impedance looks fine, the output impedance of the SLP-05 is 400 ohms, while the input impedance of the 302e is 100Kohm SE and 200Kohm balanced. No issue at all there.
The Cary gain of 17 dB single ended and 24 dB balanced is a tad on the high side balanced, it still should work fine. 
You can certainly find preamps with less gain, though they will have different sonic signature from the Cary as well.

I would think that you would be better suited by how the preamp/amp sound together then by worrying about how they look next to each other on a spec sheet. I understand impedance matching, to a point, that is no concern in your case. Gain can be adjusted by attenuators, like those available from Rothwell.  
What gain/impedance issue?
John (Jmcgrogan2), see my posts in this thread.

There is no issue with gain, although the gain specs of the SLP-05 are very inconsistent with John Atkinson’s measurements. As is the output impedance spec, potentially with greater significance. However as I said that thread:
In themselves none of these things should matter with the Krell amps that have been mentioned, given their very high 100K unbalanced and 200K balanced input impedances, and their moderate specified gains of about 25.5 db. However after noting some oddities in the measurements JA concluded by saying:
Though it has some anomalies, such as being happier with 10k ohm loads than with 100k ohms, the Cary SLP 05 offers respectable measured performance from its unbalanced jacks. I was a little disappointed with its behavior in balanced mode, however.
Which is not to say necessarily that the combo wouldn’t work well together, but it seems to me that there is cause for concern.

Best regards,
-- Al

Thanks Al, you teach me something new everyday!
It seems odd to me that a preamp would find a 10K load easier than a 100K load. Strange indeed.

I notice that the gain numbers in the measurements seem to be very different from not only the gain numbers at that time, but also the gain numbers posted on the Cary website today for the SLP-05. Whereas Stereophile measured 15.3/13.8 dB SE/BAL, the Cary website today has the gain as 17/24 dB SE/BAL (16/12 dB SE/BAL declared by Cary at the time of the review 10 years ago).

Makes one wonder if the SLP-05 today sounds anything like the one auditioned by Art Dudley over 10 years ago.