Which component to upgrade to improve bass control?

@millercarbon:

"One of the beautiful things about multiple subs, the more subs the less the room matters, and the less it matters where in the room the subs go...By the time you get to four it hardly matters where you put them the bass will be so good you won't believe it. ".

This is indeed encouraging. I don't know about fitting four Swarm cabinets into our curent living room but at the very least, I'll be able to employ them in our next abode. It was actually my wife who asserted I should have a dedicated audio room, at that point. I'd be very foolish to argue with my wife!  

"Springs go under the speaker. What the speaker is on hardly matters".

Thanks for the clarification.-- I thought the springs needed to be in contact with the floor. What happens during an earthquake, I wonder? The piano black finish on the Silverlines is fairly slick. 

@eriksquires:

"Some miniDSP units are pure digital. No analog. Another alternative is to use something like Roon, which has DSP built in".

If a Swarm won't fit, some sort of DSP may be my only recourse. I'm not technically inclined by nature so I don't exactly relish the prospect of diving into the world of DSP but neither do I enjoy sloppy bass. Perhaps you can explain why some DSP units include a DAC. What's the point? 

Why not? DAC is cheap technology today, although some (me included) like to pay too much for this...

Don't be frightened. Saying no to dsp today is like saying no to cd's yesterday. It won't stop it's the future and gets better for each day. Just get on with it :-)

Now we are moving in the right direction..

When you have sloppy bass with your bookshelf of the reasons I tried to point out previous.

How does the logic work by still playing with those sloppy bass makers and also add subwoofer/s..

Will they stop to produce sloppy bass? I do not think so.. Maybe the subwoofer/s will mask it if they play a little bit louder..

(A fix if you get subwoofer/s is (again the DSP) if you measure where in Hz you have your sloppiness and if we are lucky it is the bass reflex port that is cousing the sloppy bass and for example it is maybe between 40 and 60 Hz. Then set up the x-over in the DSP that feeds the powe amps is above 60 Hz so that your bookshelfs is not playing anything below 60 Hz.)

Regarding that maybe try to plug those bass reflex holes quick and free test. It will not play that low but maybe some sloppyness will disappear.🤔

Perhaps you can explain why some DSP units include a DAC. What's the point? 

DAC = Digital to Analog Conversation
ADC = Analog to Digital Conversation
For example the miniDSP 2x4HD:
It has a analog input there you can connect the LP and it does a ADC and in the digital domain all the magic then back to analog with the DAC.

But it has several digital inputs there it does the all the magic and then to analog with DAC.

Here is some of the whys/points when this model has 4 analog outputs that you can use however you want.. 

One example is you can choose to use output 1 and 2 as left and right that goes to the power amplifier to your bookshelfs. The other two 3 and 4 can be left and right for your subwoofer power amplifier/s.

So as you see there is four outputs in this case if you "only" got a digital out from the DSP and then connected to your standard standalone DAC that usually only give you two analog outputs. What is the point with that? Rather useless in my opinion. ;)
Then you can "only" do room correction.

In the miniDSP case the two left and right 3 and 4 output is treated individual so if you have the right subwoofer on a different distances than the left one then you can time align them separately so they are aligned with the bookshelfs.

You can implement where the x-over should be for the subwoofers and bookshelves independently and offload the power amplifiers. 

And so on and on there is so many configuration and use cases..