The benefit(s) will depend on what is needed and the precautions desired. I just bought a Parasound preamp and power amp, which means I ran out of holes in my power strip. I decided to go with a Panamax MS4000 partly so it could be rack-mounted, partly because it does provide surge protection (the voltage isn't absolutely stable here) and because it disconnects the receptacles <95VAC/>140VAC. Some do this at about 180VAC, which is too high fro most electronics to handle without letting out the magic smoke. Some are rated for 300VAC and do nothing about over/under voltage.
To the OP- if an amplifier draws a lot of current, don't use the conditioner/surge device if it has a transformer inside. Transformers limit current unless designed for extreme levels. If the lights are already dimming, make sure the electrical service is up to par- loose wires at switches, receptacles, splices in the house, in the breaker panel and at the splice between the house and the grid can all cause this. If the service was connected more than 10 years ago, have the electric company check the splices- my parents' lights would dim when the 'fridge compressor turned on/off and when the splices were checked, it turned out that the spliced wires were corroded and the anti-corrosion compound was dried out. Since voltage drop is current-dependent, this was proven to be a good fix because the problem stopped as soon as clean wire was exposed and the connectors were replaced.
