The LPS was an add on for me, i had the 20 20 for a year or so before it became available.
It added noticeable improvement in dynamics and energy and seemed to be slightly cleaner sounding. It did not seem to affect the tonal balance.
To fill in the midbass have you looked at loading adjustments, reducing gain, reducing the length and capacitance of the cable to your turntable, all depending on your current cartridge?
also not having been run in a while the 20 20 does need some re burn in time to charge the numerous filtering caps on the chassis. some say 200 hrs of power on time.