How do you know if you need a power conditioner?


I presently have my audio equipment connected to a dedicated line - is this enough? How does one know if you need a power conditioner? Are there symptoms? Does a power conditioner always improve the sound - or only in certain situations? Is there any way (short of sophisticated electronic measuring tools which I don't have) to tell if your power is relatively clean or dirty?

Thanks in advance.
studioray
I have the Q type Transformer in a box. This was listed in the clearance bin at $399. You get the q -transformer with no extra power conditioning or filtering, no ac regulation and no outlets. You have to wire the transformer into the hydro box.. and then the line out from the transformer goes secondary breaker box - (8 breakers) where you run your dedicated lines. This worked for me.. I have 4 lines with schurter connectors on the ends so they plug directly into my amps / preamps ets. (no power cables needed) I also twisted my ac lines, which helps to cancel rf, and magnetic interference.
http://www.equitech.com/
- products - used equipment and factory blems.

http://www.equitech.com/products/seconds/seconds.html