Power Amplifier Reviews

The Rotel's bass—when driving speakers full-range—was also a little less tight than that from the AMP5, particularly on crisp percussion like the drum whacks on the CD soundtrack of Master and Commander: The Far Side of the World. But this becomes largely irrelevant when your bass is routed to a subwoofer.

In both instances, however, these differences were small enough that I could probably poll 10 listeners and find them divided down the middle in their preference—if they could hear the difference at all.

End of critique. Auditioned on its own, the RMB-1077 is a superb-sounding amp. While my first-stage of auditioning with two-channel music did not stress the peak capabilities of the Rotel as much as driving five or seven channels at once, it did make it easier to grasp its essential sound quality.

On a wide variety of material the amp never let me down. The bass is surprisingly powerful—the slight softness noted earlier went virtually unnoticed once the auditions were freed of the tedium of level-matched comparisons. The top end was open, detailed, and clean. And though as noted it did lack that last whisper of air and openness at the very top end in my system, it more than made up for it with its complete lack of grit or edginess. The Rotel never bit back at me—unless the bite was a known element of the program material.

The amp also generated a precise soundstage, with a believable sense of positioning from left to right and front to back. Center soloists were precisely positioned (again, with two-channel material and just two channels driven.) It doesn't offer quite as rich a sense of front to back depth as some high-end amps, but it's very close. The Rotel gets a firm grip on the dimensionality of the source.

On Film
My system is currently set up for 5.1 channels, so two of the Rotel's channels were left idle for this evaluation.

The Rotel's 100Wpc may sound modest by today's standards. But when challenged by a demanding multichannel soundtrack, particularly with a subwoofer in the mix, it generated more than enough juice to drive my system to peak levels that no sane individual would want to endure for more than a few seconds.

I've lately been deeply impressed by the soundtrack on the HD DVD version of Serenity, reportedly encoded at 1.5Mb/sec and routed through the digital output of my Toshiba HD DVD player as a 1.5MB/sec DTS signal (for an explanation of this seeming oddity, see my recent review of the Toshiba HD-A1 DVD player .) The film's title sequence, which starts a couple of chapters into the film, begins with a few bars of the sweetest music recording this side of a first-class, uncompressed CD. It jumps all too quickly into a crushingly dynamic mix of rocket engines and more music, now fully enveloping and rising to a huge, sweepingly cinematic crescendo. As the turbulence rises, the scene shifts to interior of the ship, the music and engine noise subsiding into the metallic clattering and clanging of everything not tied down, the tin symphony spreading to all channels.

The Rotel gets all of this right, exhibiting only the slightest sense of strain on the most challenging peaks (which may well be in the recording), but never sounding harsh or grating. Dialogue and effects are treated equally well, and the score ranges from lush to explosive as the soundtrack demands.

Compared again with the Proceed amp, I noted the same slight lack of air and crispness in the Rotel's very top end. But one could just as easily argue that the Rotel is right and the Proceed a bit too crisp. The differences are subtle enough that I can well imagine different results with zippy-sounding soundtracks and/or speakers with excessive treble (there are plenty of those, though the Revels I used aren't among them.)

None of this nit-picking mattered much as I tracked down and auditioned other favorite soundtracks. I suspect we'll all be using HD DVD (and Blu-ray) Dolby Digital Plus or uncompressed PCM soundtracks more and more for reference material in the future. They're a huge improvement over their Dolby Digital and DTS counterparts on standard DVD. The Rotel sounded spectacular on the soundtrack from the Apollo 13 HD DVD, which is probably the best multichannel audio demonstration for the new format—and the RMB-1077—I've yet heard. From the now-classic launch sequence to re-entry and splashdown, the film and the system didn't miss a beat, keeping me fully engrossed in one of my top 10 favorite films of all time.

Conclusions
While I don't expect Class D amplifiers to displace conventional solid-state amps overnight, I wouldn't be surprised if they eventually dominate the market. In the Rotel RMB-1077, that future may be here now. This is an outstanding amp by any standard—Class A, A/B, or D.

Keep in mind too that if the RMB-1077 doesn't offer enough power for you, Rotel has just released two new amps using the same ICEpower technology, one a monoblock ($1499) and the other stereo ($2499). Each offers a teeth-rattling 500Wpc!

Note: A minor flood—aka a badly soaked floor and carpet—has required us to evacuate the test equipment from our lab space and allow the room to dry out. The measurements for the RMB-1077 will be posted as a "Take Two" in the near future.

Highs and Lows

Highs
Excellent overall sound
Seven channels of solid performance in a light, compact package

Lows
Bass could be tighter
A subtle lack of air and sparkle in the upper treble