How to improve power supply?

09-17-14: Ptss
Hi K.
I know it's deficient because of the "inordinate" gains I obtain from using a 'combination' of ac power isolation & conditioning devices bought to enhance my listening. I am using -and need to use- an Equitech 2Q balanced transformer, MIT AC2 & AC1 reference power cords, and MIT Z Stabilizers--all to excellent effect.

this is a totally wrong assumption on your part. Even if you improved your in-chassis power supply, you would still need the AC isolation & the Equitech. Almost all the power & pre power supplies are unregulated so they are quite sensitive to the grunge on the AC power coming out of the wall socket.
The AC isolation & the Equitech unit is cleaning up the AC power coming into your electronics & it will still need to be in place after you upgrade your pre & power supplies.

Now, your power supply caps probably need to be replaced as correctly suggested by Rodman99999 simply due to the electrolytic dielectric material drying up over a period of 20 years. You could also gain by using HEXFRED rectifier diodes, I agree with this.
But you will still need the AC isolation & Equitech after all these upgrades.
IMO you could get rid of the AC isolation & Equitech if you had a regulated power supply (like a SMPS used in many class-D amps). A regulated power supply will maintain regulation over a wide range with very little output ripple & will also have good load regulation (i.e. minimal output voltage changes when the load current suddenly changes. Sudden changes in load current are expected as a normal when listening to music which is quick moving signal).

Ptss - Don't get too wrapped on what is being used by NASA, NOAA, NSF, etc. We are talking about audio systems, not GHz telecommunication systems to Mars. The Plitron will dramatically outperform the kiddy toy power transformers in 90% of those used in preamps of the 90s and later.

Thanks Bomb. I don't want to start a disagreement but in my understanding regulation does not provide "clean" power. It provides a degree of stability, ie regulation within given parameters. I may not be up on the latest facts so I will do some research before commenting further. When I complain the PS is inadequate it is based on the statements by the products representatives when I bought the units new-- that the PS made the pre virtually immune to ac powerline disturbances(noise). Oh well, I will look into the info that has come into this thread and probably have more questions. I'm not in the least interested in technical aspects but a degree of self education seems helpful in this hi-fi / well , music listening hobby. Thanks for your input.

Like many other electronic components; regulators generate noise. A number of ways to address that noise have been discussed and tried, by hobbyists and companies. ie: (http://www.edn.com/electronics-blogs/the-practicing-instrumentation-engineer/4422750/Simple-circuits-reduce-regulator-noise-floor) (http://www.diyaudio.com/forums/solid-state/1437-reducing-noise-voltage-regulators.html) (http://www.belleson.com/comparenewclassd.php) (http://www.belleson.com/compareburson.php) (http://www.ti.com/ww/en/analog/tps7a30/index.shtml?DCMP=hpa_pwr_tps7a30&HQS=Other+OT+tps7a30-bt2)

Hi Rod. My biggest efforts have been to remove noise. Equitech balanced power, MIT, Furutech. All to "great" effect. Love that silence.