Multiroom devotees have plenty of options: the AVR 635's rear-end facilities include an RS-232 computer-control port, IR inputs and outputs, and Harman's A-Bus multiroom system.
There's nothing like an over-the-top special-effects DVD to test the fortitude of an A/V receiver, so we popped on The Day After Tomorrow and let 'er rip. The DVD's battery of effects were vividly presented: the tsunami wave crashing into Manhattan, check; countless scenes with windows smashing to smithereens, check; arctic winds so fierce we could sense the granularity of the snow, check--the Harman Kardon AVR 635 consistently unleashed an incredibly realistic sound experience.
Not only did we feel the impacts of the cannonballs on the Master & Commander DVD, the men's boots thumping over the wooden decks sounded like they were in the upstairs apartment! We nudged the volume up and never detected a power shortfall; the 75 watts per channel felt pretty darn powerful.
We next sampled the high-resolution DTS 96/24 sound mixes on Peter Gabriel's Play DVD. The mixes were particularly enveloping, and bass detail and definition pumping through "Games Without Frontiers" added a new dimension to the music. And that's exactly what separates the AVR 635 from the better $500 receivers: the Harman Kardon sounds bigger and more flesh-and-blood present, so it opens up the sound of DVDs and CDs in ways that more affordable receivers can't match.
We heard impressive clarity from the AVR 635 on a series of boogie-woogie piano duets from the Rockin' the Spirit CD. Fully reproducing the sound of a pair of concert grands is an impossible task for any audio system, but when called upon to deliver the instruments' wide dynamic range and weighty presence, this receiver's graceful poise clinched the deal for us.