If you like to rock or simply enjoy a very dynamic, low distortion presentation, increased headroom in both the speaker system and amplifiers is ALWAYS beneficial. From what i can recall, i've been preaching this idea for several years now. Glad you like it and hope it only gets better with time : ) Sean
>
PS... If you're a "rocker" on a budget and don't mind buying older used gear ( you're already on Audiogon, right??? ), two Klipsch Heresy's per side with four large home-brewed sealed and stuffed subwoofer drivers per side is a hard combo to beat. Very punchy mid-bass, solid vocals, plenty of bite in the guitars, pronounced cymbals with an extremely fast and tight bottom end that exhibits plenty of oomph, etc... If you can buy the raw woofers and build the cabinets yourself, the four Heresy's and sub system should run you about $1000 - $1200 at mosst.
Two NAD 2600's for the Heresy's and a beefed up Phase Linear 700B for the bottom end will get you over a kilowatt of power per side for around $1000. At appr 98 dB's of sensitivity for the dual Heresy's, the system will rock quite well without putting a massive strain on any of the amps. The slightly "mellow" NAD sound works pretty well to tame the potentially glaring horn sound of the Klipsch in stock form. The fact that all these amps have variable input level adjustments allows you to fine tune the balance between the Heresy's and the subs without the need for an active crossover. That is, if you want to keep the cost down and run passive subs.
Having said that, an active crossover will sound better and improve the performance on both the subs and Heresy's if you can swing it. Use the sharpest slope possible and keep the crossover point at around 40 - 50 Hz or so. Going higher in frequency will increase the bass weight of the system and potential dynamic range of the mains, but as you go higher and roll more of the bass out of Heresy's, you may notice that the kick drums will lose some of their "snap". This all boils down to personal preference here.
Personally, i prefer the Heresy's to La Scala's in stock form for most any type of music. They may not be as efficient, but they sound much more natural. The La Scala's require a LOT of work to really make them sing and most people aren't up to the tasks required. Besides that, the two Heresy's will cost less than one pair of La Scala's and take up less floor space / aren't nearly as ugly.