Which component to upgrade to improve bass control?

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..

@gosta:

"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 :-)"

Got it. Thanks. 

@optimize:

Thanks for the technical explanation. 

stuartk: Before you get involved in all the expense and to-do of all the good suggestions so far, are you using AC conditioning and upgraded AC cables? Both will really affect bass definition. Especially in multi-unit buildings. Even if you do all of the things suggested here, you’ll still need to upgrade cables to maximize the system.