Parametric EQ Suggestions / DSP in Roon?

[David A]

… That said, I did some googling, and apparently the crossovers inside most speakers include a high-pass filter designed to match the abilities of the speakers—but if that is the case, how can SAM work its magic by dropping the bass floor in so many models?…

It's hard to find any real detail about how SAM works but the little I've seen from Devialet mentions 2 things. One is control of the maximum woofer excursion which is really a speaker protection function. The other is a statement that SAM applies phase correction over the range in which it operates.

If you take a look at any speaker test reports like the ones that John Atkinson does in Stereophile, you will see that there are large phase swings in the bass region for most speakers and SAM is supposed to operate from 150 Hz on down. Check that area in the phase plots in Stereophile's speaker tests and you'll usually see some very wide ranging phase swings.

I was re-reading a bit of Floyd Toole's book "Sound Reproduction" a few months ago and I have a memory of seeing a comment to the effect that phase correction in the bass frequencies can effectively provide up to additional half an octave or so of bass extension for many speakers. Devialet claim that SAM provides more added extension than that for a lot of speakers but then I don't know what SAM is actually doing and whether it's doing more than just providing phase correction in order to deliver the extension it provides.

Whatever SAM does, it isn't changing the operation of anything in the speaker's own crossovers, it's changing the signal sent to the speaker. If the bass driver has a high pass filter operating and controlling its roll off at the low end of the speaker's range then that high pass filter is still going to be doing it's thing but it probably isn't a "brick wall" filter with a steep rolloff and it's probably operating with a 6 or 12 dB rolloff per octave. Let's say it's 12 dB/octave with a frequency of 20 Hz. That means that the level will be down 12 dB at 10 Hz from what it was at 20 Hz and that's roughly equivalent to a bit over a halving of perceived volume. While the speaker will be rolling off, the room could be providing considerable support at those frequencies depending on the position of the speaker in relation to adjacent walls and also on the location of the listening position and in-room response at low frequencies is usually quite different to the speaker's specified frequency response which is usually an anechoic measurement. I don't know how Devialet measure speakers in order to determine the frequency to which SAM provides extension but it is probably not the same way that the speaker manufacturer measured the speaker's response for the specification info they provide and that could make a big difference because some speakers with good setup in a room are capable of providing more than half an octave of bass in room over what their specification suggests. Add that to whatever extension SAM delivers and you could be seeing the sort of in room response claimed for a speaker using SAM ***PROVIDED*** you're in the room in which Devialet made their measurements and listening where Devialet had their microphone located. In another room with different speaker and listening position setup you might notice more bass with SAM but measurements might fall short of the range stated in the speaker's specifications. Low frequency in-room response of speakers is "highly variable" and often bears little similarity to what is claimed in the speaker's specifications, especially if the specifications are based on anechoic measurements.