That depends, Richard. Just like any other product in this world, there are some to many line conditioners that simply are not worth owning. And for good reason. Some of which include:
1. They induce their own shortcomings by suppressing certain frequencies. Much like some components (expensive ones too).
2. They are current limiting. (Not a good thing for many amplifiers.)
3. They simply don't offer any sonic improvements whatsoever.
4. They actually induce additional noise into the AC.
On the other hand, dedicated lines do nothing to condition or purify the AC. And all AC is dirty to one degree or another. Dedicated lines still carry every last bit of noise on the AC to the components. Only now the noise is dedicated just like the AC. Hence, a seperate line conditioner is now required to purify the AC for each dedicated line installed.
To the best of my knowledge, dedicated lines are advantageous for only two reasons:
1. They help keep other AC noise (generated by household appliances, dimmers, etc., and digital components such as cdp's) from contaminating the other components on their own dedicated circuits/lines.
2. They help ensure that power amplifiers (especially high-powered amps) get all the juice they require for even the smallest of dynamic passages. In my case, even a 30watt preamp on my 20amp dedicated line was just enough to choke my amp. Putting the preamp on it's own dedicated line caused the amp to absolutely come alive.
But it is essential to realize that the dedicated lines do nothing to purify the AC noise coming in from the street.
Back to the line conditioners, besides inducing no sonic harm, a properly designed line conditioner should provide a minimum of the following benefits:
1. Complete or near complete elimination of negative sibilance.
2. Provide ample current to an amplifier.
3. Provide a lowered noise-floor/blacker background. (No matter how low a noise-floor you think you may have right now.)
4. Enhanced 3-dementional soundstaging.
5. More precise/pin-point imaging.
6. Greater transparency.
7. A better defined bass region.
8. Perceived greater dynamics. (musical notes being generated from a blacker background will always give this perception.)
9. Greater resolution. Hearing little nuances that you did not realize were there.
10. Allow you to enjoy the music at more exciting listening levels without inducing listener fatigue.
I'm using the Foundation Research LC-1's and LC-2's passive in-line power conditioners. These are dedicated one per component, and obviously are a natural compliment for those with dedicated lines. Come with their own built-in power cable, and cost about as much as a good power cable.
Marty DeWulf reviewed these in the Aug, 2003 issue of Bound for Sound and rated these the best he's heard and purchased the review samples for his 'Big Rig'. Endorsements don't get much better than that.
Purchasing the right line conditioners will simply allow you to hear more into the recording and thus provide a substantially improved musical presentation that along with the right caliber of equipment, will make it very difficult to get to bed before 3 a.m..
-IMO
