Other information that is not known, is how the TT is mounted?
Is the TT sharing the same structure as a seating the Speakers are seated on?
Speakers at 20"s Tall will usually be mounted on a Stand or Sub Plinth and Stand that is typically not much more than 24"s inches in height, but usually between 18" - 24" depending on the height that is ideal for the Tweeter. Usually the Tweeter is a little above ear level or on the same height level as the ear, when stands are being selected.
As a conjecture, is the Side Board 36"s ?
Are the Speakers Toed on the Longitudinal Plane if the Tweeter is too high, in conjunction with being Toed on the Lateral Plane? Getting this alignment correct will take a additional amount of tweaks, and Pads as footers on a Speaker are not offering the finesse of adjustments that may be required. A Sub Plinth under the Speakers will always being a improvement to how tidy a Cabinet Speaker End Sound is being perceived. In this case it can be suggested a Sub Plinth with Footers that offer a broad range of adjustment will be the best suited design. The Pads already in use will be useful for the Speaker on the Sub Plinth, but again I strongly suggest a suspension type footer for this role.
Getting the mounting method correct will be beneficial to any Speaker put in to service, the time spent will be future proofing.
The TT is much much more sensitive and getting the mounting structure correct for creating the environment the stylus function at it best will yield great rewards, again getting this correct for the environment the TT is set up in will be extremely beneficial if changes are made for a TT further down the road.
Both the above mounting methods are not going to cost much monies, there are DIY designs that are extremely effective, the main cost could be how it is appealing aesthetically. On a Cabinet, a method to keep costs down, I would suggest looking at Kiln Dried Sand Filled Plinths.
