Socrates: Have you verified that all of your gear is wired to the correct polarity ? Try taking a look at this thread regarding AC noise, hum and polarity
before dumping a lot of time and money into what might amount to nothing.
Personally, i found the 2500 to work quite well at lowering the noise floor and cleaning up the overall presentation, but i also noticed a small reduction of "liquidity" and increased "sterility" within the system. Swapping to an Adcom PLC brought back some of the musicality but also raised the noise floor and let "transient pops" from light switches and the fridge kicking on right through the system and into the speakers.
Obviously, i was looking for something in-between the two extremes. Switching over to individual iron core isolation transformers pretty much gave me the best of both worlds, but is nowhere near as convenient or neat in appearance. I'm working on building a "one chassis" device to alleviate some of the clutter. I am still using the 2500 in some of my systems but intend to replace them as the opportunity arises.
Having said that, i also tried three of the lower scale Monster PLC's. Two models, which are basically identical yet have different model numbers, actually introduced noise into the system. As such, they found their way into my "parts bin" to be dismembered at random. The 2000 seems to work along the same lines as the 2500 ( give or take ) but "creates more wire clutter" due to it's layout with less over-all filtering capacity. I have not done any side by side comparisons between the 2500 and 2000, so don't know if one is more "liquid" or "veiled" than the other. However, i do know that both are quite good at filtering out the mass majority of line noise and transient surges. As such, i can recommend them if one is having problems with either of the above with the caveat's mentioned above.
If i was going to modify a 2500, i would start by replacing the line cord to a model of ones' choice. I personally prefer a line cord with very low inductance and high capacitance of more than ample gauge. If you are using the device for line level gear only, shielding could also be beneficial. I would avoid shielding a power cord for amplifiers as i have yet to run across a commercial model that does so in what i consder to be the "most correct" manner.
I have also found some connections within the device that were not up to snuff. This is typical of ALL mass produced items that i've seen. As such, i would re-flow all of the existing connections with a high quality solder. The important thing is to properly heat the joint and THEN flow the solder into the connection. Globbing more solder on top of ( rather bonding with ) existing connections does nothing but make a sloppy mess.
Other than that, one might try replacing the outlets with models of your own choice, but that would be a last resort as it is somewhat labor intensive. Then again, re-soldering the entire board is pretty labor intensive, so you could probably do everything ( power cord, outlets and reflowing the board ) all at once and be done with it. Sean