Amp matching with high sensitivity speakers

You’ll be fine. Unlike most audiophile speaker makers, Klipsch also has to serve the Bud Light party bros and home theater nuts who will absolutely THRASH their speakers at absurd volume levels. That warning and its very conservative amp power recommendation is intended for them, not you and I - proper 2ch audiophiles 😉

The risk with clipping from too little power is specific to the tweeters, which are normally designed & spec’d to handle MUCH LESS peak and continuous power than woofers. The tweeters are protected by a high-pass crossover plus the fact that most power in musical content resides in the lower frequencies. However at instances of hard clipping (especially with SS amps), the clipped content has peaks which measure at TWICE the max continuous power rating of your amp and at very high frequencies to boot. This effectively goes right through the high-pass filter (because it’s comprised of high frequencies, even if for a very short instant) and sends these power peaks directly into the tweeter. That’s bad, and this is why clipping is considered a tweeter killer. It also sounds like SH*T and hurts your ears badly because high frequency content at such high levels is extremely unnatural.

But the reality is that your 100+ dB speakers will make your ears bleed long before you hit hard clipping with any amp north of say 10 Watts. Also, if you choose a tube amp or a single (which is more likely at lower power classes), it will naturally soften the clipping a bit, which reduces the peak power sent into tweeters. Also the First Watt amps, being class A without much (if any) global negative feedback, should likewise feature more gradual clipping (I think). So I wouldn’t worry about it!

There’s no problem driving them with your 300 Watt amp, just be careful with the volume control. Again, your ears will bleed before the speakers are in danger.

I have 96 dB / 2.83V Tannoys, and I’ve definitely noticed that noise floor is something to be mindful of. Any power amp by itself, whether tube or SS, should not render audible hiss or hum. The problem is that the amp’s gain will magnify your preamp’s noise floor (from active circuity after the volume control). So the more gain your amp has, the lower you need the preamp’s noise floor to be. Active preamps with a higher gain tend to have higher noise floor, unless their signal-to-noise ratio is also higher. Tube preamps with high gains (> 14dB) are usually asking for trouble. I can really hear the noise floor of many preamps in my system.

The ARC Reference 6 has an extremely high signal to noise ratio, so despite its relatively high 14dB gain, it’s dead quiet in my system. Most other tube preamps, I can hear varying degrees of hiss noise with the volume at 0 (not muted).

In modern times, a SS amp will have higher gain in order to facilitate tapping into a very high power rating (you need a lot of gain to push out say 400+ Watts). However, a lot of the lower powered tubes amps will have a surprisingly high gain because using a 12ax7 V1 tube was popular, and analog sources of that era had low output levels so the extra gain was welcomed (for example: the Eico HF-87 tube amp required a meager 0.38V input to produce full rated power of 35 Watts!). So even when you go to lower power tube amps, it may have similar gain to your much more powerful SS amp. This means you should be very careful if you’re selecting a tube preamp to pair with it, or you will hear its hissssss noise!