It’s not a serious mismatch per say, it just appears you’ve got a high gain tube preamp without the highest signal-to-noise ratio. Your Doge lists "200mV sensitivity" - if that is in reference to a 2V output, that’s 20dB gain which is very high. Generally, when you get a tube pre up in that range you’re gonna hear low level hiss noise at output (from speakers) unless your speakers and/or amps are low sensitivity. Your amp’s gain (27.6dB) and speakers (91dB) are sufficiently high that this noise floor is totally expected. Tube power amps almost always have pretty high sensitivity / gain - even low power ones like yours!
So now it’s just whether the noise bothers you enough to cut it down with that amp potentiometer. You might try a little and see if that sounds "transparent enough" for you.