Level the floor

My wood floor is nearly identical to your slope, it is down 3/4" within the first 24" from the wall, then very little slope after that.

My existing rack, bentwood and glass has supports in the back and sides.

I cut new end ’feet’, hard maple, and tapered, 3/4" higher in the front. Note, they extend a few inches past the back and in front of the rack. Big screws with lock washers hold the new supports to the existing end pieces. Not only level, but increased stablility due to extension of the supports..

Again, trying to understand the problem. The only item which MUST be level is a turntable, and that is usually easily fixed.

Otherwise, so long as your floor is flat there's no real issue I can detect.

eric,

even if the turntable is leveled, in OP's case by putting 1" high 'lifters' under the front feet

if your rack is pitched forward under the turntable, the combined weight of all other components is also pitched forward, fronts of each piece lower than the rear, add the combined weight of my 3 glass shelves pitched forward: any vibrations will more readily rock the rack forward then back ...., it is far better to level the rack and have all the combined weight be a downward force.

The only item which MUST be level is a turntable, and that is usually easily fixed.

Right.  This floor is not flat.

As discussed (and, okay, discussed...), this is some serious tilt.  I wouldn't want to have a desk that tips this much.  Okay, so, stick some books under the desk -- 'tis the way -- but sound-making machinery is prone to Surprises and I didn't want to learn that I'd solved this the dumb way when I heard a bang.  So, I asked.

Turntable: pucks.  Huzzah.

Speakers: I wouldn't want to run those on a tilt either.  Call me picky, but this set is modular, irreplaceable, with some heavy magnets at the top, and this much tilt makes me nervous.  I also want to be able to adjust them, the floor is carpet, that can cause surprises, and and and.

I've learned, for which I'm grateful.

OP:

Each issue has it’s own fix. Speakers often have adjustable speaker feet/spikes which can be used, as well as speaker stands with adjustable feet.