The hiss levels produced by some amps which may be perfectly fine with say 90 db speakers could very well be bothersome with 102 db speakers.@almarg That's usually more of a preamp thing. Most amps are plenty quiet to be fine on a speaker of 102dB.
@lordrootman One thing to be aware of is that the distortion of an amplifier makes a much bigger difference when dealing with a high efficiency loudspeaker! Solid state amplifiers are well-known for brightness and harshness; this is caused by the higher ordered harmonics they make of which I mentioned earlier. One thing I did not mention is how keenly sensitive the ear is to these harmonics- this is because it uses them to sense sound pressure over a 130dB range. So keenly sensitive is an understatement. That is why the 'very low' distortion of many solid state amps is nevertheless audible.
Most push-pull amplifiers, whether tube or solid state, have a character where there is a certain minimum power below which distortion actually increases. There are only a few push-pull amps where this is not the case (ours are some of those few). This is the origin of that 'first watt' thing, where there first watt has to be a good sounding watt. On your speakers this is going to be critical. On that account 99% of all solid state amps should be ruled out; if you really want to go solid state your options are few. The Nelson Pass First Watt amps are your best option in that regard.
But if you go with tubes you have a few more options! You don't need a lot of power (25-30 watts at the most in most rooms, provided its musical power). A lower powered tube amp with high resolution will bring you more satisfaction. I think it a very good idea that you do a shoot-out, since you probably want to get the most out of your speakers! Do an audition of some of the top contenders (tube and solid state) and I think you will see what I mean.
One further note- the amplifier will not need a lot of gain- 20dB will be plenty. We have quite a few horn customers; normally our amps have about 25dB of gain but with a simple adapter plug we offer, the gain of our amps can be reduced to about 15dB which knocks out a lot of the noise floor that you will encounter with many preamps. For this reason, many low powered SET amps have only about 15dB since they are intended to operate on high efficiency loudspeakers.
The bottom line here is take your time. What is important is that when you play the system, it convinces you of music and you want to spend time with it- that is what the investment is for. Matching the amplifier to horns is always critical, but if done properly the payoff is huge. I recommend bringing in your significant other (as long as the two of you enjoy similar music) as this whole thing works better if both of you enjoy the presentation. Above all- have fun!