What if the speakers I want don’t have SAM profile?

[Jean-Marie]

The QR1 can only go down to 45Hz, but with SAM it can reach 26Hz, so better than the SR1.

So if the 3x price of the SR1 justification is the bass compartment, I would give a serious consideration to the QR1+SAM. 

This is true only for limited SPL.

Gain which SAM adds is not for free. The cost for every additional 3 dB is doubling the power which is used - and the power on Devialet 120 is pretty limited.

That’s true, but the SR1 is not a 3 way floor stander while the QR1 is a bookshelf. Both are bookshelves with approximately the same volume and only 0.5 inches difference between the woofers. 
This is typically a situation where SAM will make a difference even with a D120. 

I used to run my speakers with a D120 before upgrading to the D220, and I was rarely operating beyond -6dB which was giving me that headroom for SAM. 

Jean-Marie