Finding the right tube preamp (input values) for Mccormack DNA

Forgive me but how do I determine the input sensitivity on any particular tube preamp? 

I have tried to figure it out some manufactures are easy and label it but some have a lot of values and with my limited knowledge of values and current specs I find it hard to figure out which is a good match.

I have a Mccormack DNA-1 Deluxe and am looking to add a tube pre. I have seen the likes of Audible Illusions, Conrad Johnson, BAT, and others who are good matches but I would like to possibly see about modern gear for a good match. Like Jolida, Rogue and Odyssey to name a few. 

What are the specs I am looking for to see if they are a good match? I have read the Mccormack has input value of 10v.


@photodusty -- I think the problem with tube preamps is more with Steve's amps with his higher-level revisions (A, Gold, Platinum, etc.) rather than the stock or Deluxe models.  If memory serves, input impedance on models with certain revisions was quite a bit lower than 100 kOhms, but this may vary by model and revision level.  As mentioned earlier, you should be fine in most cases with your amp. 
@soix I believe you are mistaken.  I asked Steve Mc about input impedance and was told that it remains 100k after his SMc Audio upgrades.
See, now even more confusing. 

So when looking at a preamp, what values what am I looking for?...some say 10v some say 100K some say 28db volume.....etc....

You want a preamp with plenty of overhead, so at normal volumes it makes no distortion. That might be that 10Volt figure, although IMO that's a little low.
Since you have NHTs the gain might be handy although most tube line sections won't have 28 dB- 15dB is more comon. The input impedance of your amp is 100K (single-ended) and so nearly any tube preamp can drive it.