I have a room similar to yours, 14 x 24, 8’ ceiling
https://systems.audiogon.com/systems/9511Been here for 43 years, had a few different speakers here. My favorite speakers are my current vintage horn tweeter, horn midrange, 15" woofer. (see photo of speaker’s innards)
You will find, with horns, with proper balance of highs/mids/lows, you will listen at lower volume than prior ’normal’ and enjoy amazing imaging/detail with no need to concentrate, just enjoy.
Those speakers should not produce listener fatigue IMO. Concentration to ’hear’ ’be aware of’ imaging/detail is the source of listener fatigue IMO.
High efficiency of any speaker will be a great advantage regarding smaller amp, probably tubes eventually, not just smaller price, also less weight/size/heat, more placement options (remotes require direct line of infrared beam).
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Of your choices, I would ask for a customized pair of Volti Razz.
I would ask him to include a pair of high quality L-Pads, to allow you to alter the balance of mid to woofer and tweeter to mid IN YOUR SPACE! You may never alter them, but, like my 3 way horns/big woofer, I bet you will.
He would need to change the crossover so that his ’normal’ frequency response is designed for mid-attenuation (like most famous speakers did in the old days). Not rocket science, I bet he would enjoy doing this.
Then, for each/any listening space you can reduce attenuation for dull rooms, increase attenuation for live/bright rooms, and your personal taste, and perhaps boost the highs a bit as you age. You may use them in a different room someday.
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Loudness: any preamp you buy, look for a ’loudness’ circuit to boost the bass at lower volumes, the ability to still hear bass (jazz or rock) will keep the low volume music involving, that’s the difference to keeping low volume from becoming ’background music’.
https://en.wikipedia.org/wiki/Equal-loudness_contourmisnamed/misunderstood. should be called ’low volume eq’ or ....., not loudness.
I use a Chase Remote Line Controller, RLC-1 with 2 methods: automatic fletcher-munson bass boost is progressively engaged as you reduce it’s volume, and remote volume/balance/bass/treble from your listening position, centered, or off in a corner while someone else is sleeping.
When you have superior and more easily discerned imaging, I found a very slight balance adjustment to an errant track can make a surprising difference, everything ’opens up’, easy to hear the results.
Something else in-line? Heresy! Once again, probably over 10 times, I have proven to myself and listening friends that we simply cannot hear any difference with or without it. 120db s/n seems to be true.
best of luck, Elliott