What is wrong with my system?

Make sure you listen on midrange axis where these speakers seem to be designed for. Not on the tweeter axis.

Next, the room.  These speakers in an untreated room are goint to put out far too much upper treble energy.

Upgrade the fuses in your monoblocks.

Sugden Masterclass LA-4
I’ve rerplaced every AQ cable I’ve owned.
The recommendations are all over the place.
Basically you are on your own like everybody else. If you remotely agree with anyone stay close to them until you don’t.

nice stuff, so investigate, patiently, before spending any real money.

my first instinct is to buy all common in-expensive cables, lamp cord for the speakers, change them all. listen, clues?
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no significant difference, it’s the speakers and/or the preamp.

add sub(s), or change preamp?

bring in some other speakers you can borrow or return, see how they compare?

buy a pair of inexpensive Rockville subs you can easily return, just to learn something? two, not over-sized, a ’stereo pair’ of front facing subs adjacent to the mains.
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difference from cables change: then put the cables back one set at a time,

speakers only: differences?

preamp to amp?

primaty source to preamp?

as soon as you hear something you know is non-imaginary, better or worse:

before proceeding, leave that change and go backwards, reverting to in-expensive cable, IOW, just that change, or a change due to the last one and any prior.

I’m exhausted thinking about it.

You will prove things about the cables as you go.