Hi Brendon,
Im 25+ years an Audio Visual Installer and general fault finder (I also own the company

) . That does not mean I know everything, But it does mean I get daily faults to find, Some are common faults but many are still faults for the first time......You must be open minded about this.
Being VERY blunt here......
If you are going to look at ANY system with an issue and use the statement "I really doubt its "X" bit of kit or cable thats the issue" Then not only might you miss what the issues actualy is BUT you are also making your own job so much harder to do........
Side note : my ?1500 Denon 3800 player has always worked fine, last night it jumped all night ling so I dragged a spare unit in, My Mark Levinson CD Transport had always been fine then one day the draw started to stick half way out, My Sony ES player one day refused to turn on, My Quad Electrostatics needed a HF panel, ALL of these were fine days prior. Some of your system has been switched off, boxed up and moved to a new location things go wrong......
I think you have been through a lot recently with the move and changes, Give the Hi Fi a chance, It will be worth it.
Andy - Steps off his soap box

The reason I mention to change the cables round is a phase check and BASS is most changed by this.
By changing the peaker cables round you are acually checking the ENTIRE audio signal cables from the CD all the way to the speaker - You are rversing the entire chain. So IF this helped then and one OR MORE cables could have a phase reverse, that could also be in the other channel........
PS - If the complaint is that the system sounds flat that could just be you are hearing it correctly, There should not be an area of the audio that sticks out unless its a solo.
Basic set up tools include phase checking and test tones, I really urge you to get the shop in to do the install correctly - Then if there is an issue they can sort it at their cost.
PPS - If you heard more bass in your previous system another way of putting that is that you had less mid/HF in your previous system. As speaker systems go up in quality the ability to reproduce lower frequencies increases thats NOT louder bass but deeper/lower bass , That will also mean the bass will become more subtle much play much lower. The B&W 802D has the near perfect bass driver compliment (the 800 being perfect) so there really should not be an issue there. ALSO the 802D has the supertweeter that can sound a little sharp and detract from the rest of the reproduction until the entire cabinet has run in - Speaker run in is essential, (I am amazed that companies dont do this prior to shipping)
Speaker placement also greatly changes the sound.
Sorry if this is unstructured and blunt response in places - I certinally dont mean it to cause offence - I have just got in from a Time Trial on my push bike and still running on caffine

with a more erratic than usual thought process

.