CDP isolation options for improved HF?

Following recent thread on shelf material, I'd appreciate advice on supplentary isolation/vibration devices for my old CDP (Rotel 855). I'm mulling over new digital front end options, but meanwhile want to eliminate HF roughness now evident in my new ref system, without reducing PRAT or resolution. So how do I optimize the use of this CDP until the revolution? Some have suggested that air bladder suspensions compromise timing. Is this often true? Thanks. Ernie