I should add I am looking for Preamps under $1500. I also have NHT 3.3 speakers.
@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.
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.