Spatial M3 Sapphire or Klipsch Forte 4

Based on your room  and seating position and having subs that you could cross at40hz… the Sapphires would do what you want and more… but they really do need 3-400 hours of break in… and at least 45” from the front wall and 2’ from the side walls.

how loud do you listen?

How loud do I listen? Ive never gotten a db reading on it. But if I had to guess, I’d say around 90 to 95 db.  

How loud do I listen? Ive never gotten a db reading on it. But if I had to guess, I’d say around 90 to 95 db.

op

https://www.noisyplanet.nidcd.nih.gov/parents/too-loud-too-long

there are free smartphone apps to check db levels, average and peak... you may want to spend a few minutes to see...

this nice little calculator will allow you to get a ballpark idea of the volume you can achieve with various wattage.

https://myhometheater.homestead.com/splcalculator.html

I would think that your single ended tube amp will give you a really nice midrange, top end and soundstage but not the best control of the woofers for the really deep stuff...but if you are committed to staying with the subs...then it might not matter.

There are a lot of threads on AC regarding the spatials and how they mate with low power, high power, solid state and tubes....and how they compare to other speakers...they are worth reading...

Here are a few  links..... 

https://www.audiocircle.com/index.php?topic=180075.0 

https://www.audiocircle.com/index.php?topic=180361.0

https://www.audiocircle.com/index.php?topic=180031.0

I own the M3 Sapphires driven by a PrimaLuna Dialogue Four. This is a push-pull amp that can be used in either ultralinear (42W) or triode (21W) mode. I prefer triode mode. I listen really loud at times to a wide variety of music. Very open, realistic, and dynamic sound. The soundstage is very much behind the speakers, so if you prefer a more intimate presentation (i.e. performers in the room with you) this may not be to your liking. The Sapphires are more like sitting in a large auditorium watching the performers. Bass is tight, accurate, and detailed, but to some may ultimately lack sheer slam and heft. It’s not that the woofers are insufficient–there’s four 15" paper cone woofers that can move a lot of air. Rather it’s the open baffle design and lack of cabinet reinforcement and resonance.

Klipsch’s are also very dynamic and usually extremely efficient. Low power SET amps can be used. I’ve only heard Klipschorns, but I would say if you mainly listen to classic rock and want to listen loud then the Forte IV’s may be more satisfying. The Sapphires will sound completely alien at first, but once you acclimate to them you will appreciate what they bring to the table.

This is all to say audition them both if you can. Since you owned the Forte III’s you have a good idea of what the Forte IV’s will offer. The Sapphires will be different.