Rotel RMB 1095 (5ch Power Amplifier)

Setting up the Rotel amplifier involved sending the multi-channel preamp outputs from the Yamaha RX-V2500 to the RCA line level inputs of the RMB-1095. Since I was only using 5.1 plus the Yamaha’s presence channels, the lack of the two additional amplifiers for 7.1 did not bother me or affect my setup. When using a receiver as a preamp you also gain the advantage of being able to utilize the onboard amps for additional channels not covered by the receiver. For example, I utilized the Yamaha’s amplifiers for the presence speakers which I engage during certain movies where I feel it would be nice to experience additional DSP effects.

The first thing I noticed upon connecting the Rotel and powering up the system was a very loud ground loop buzz coming from my speakers. After some basic troubleshooting I realized that it was a ground loop between the cable TV line and the Rotel amplifier ground. This is probably the most common ground loop encountered by many adding an amplifier with a three prong power cable. Adding a cable TV ground isolator from Jensen Transformers fixed the problem entirely. I was so impressed by the transformer that I actually wrote an article depicting the problem and highlighting the solution. If you encounter this in your system, don’t pull your hair out. Simply disconnect your cable TV line from the wall. If the buzz goes away then buy this product.

The Rotel amp didn’t really run hot for me during the testing period, and I provided it tons of ventilation. The heatsinks did a great job and to be honest, the amp is built so well, you really have to feed it a lot for it to break a sweat. Putting it into a cabinet requires at least 10″ of clearance so you’ll have to avoid wimpy racks and may need to reposition your shelving to allow for adequate heat dissipation. One of the coolest physical features on the amp is the presence of two rear low-profile casters that allow the amp to roll back into place once you have it inserted into a shelf or rack. This is a life-saver and shows some excellent design thinking on the part of Rotel

Listening Tests

So far the Rotel RMB-1095 has shown itself to be a versatile, well-constructed, powerfully-equipped device with the look of a serious home theater component. Its sound was next on the list and I decided to start with some very familiar material. As ever, I strove to provide a real world experience, so I compared its sound to a $1000 receiver – a likely upgrade waiting to happen.

CD: Steely Dan Gold
Popping in Steely Dan’s Gold Album, I queued up Track 1 “Hey Nineteen” and listened carefully to the first minute of the song. There is some very tight instrumentation within this track and lots of room to observe distortion and an amplifier’s ability to effectively control the loudspeaker. What I found was that the receiver provided a softer sound, slightly muddied in the lower midrange. The RMB-1095 rendered the intro so cleanly compared to the receiver, an unprepared listener may think something was missing.

Editor’s Note
I placed the receiver into Pure Direct mode so that all DSP was bypassed and the main channels were handling full range signal. While I will talk about 5.1 home theater later, all of my direct comparisons were done in this method using only two-channels. An SPL meter was used to ensure a ballpark equivalent SPL was maintained when comparing between the receivers internal amps and the Rotel.

In truth, the Rotel amplifier is giving you a more accurate representation of the soundtrack. It’s not a fair comparison, really, but it is important to occasionally demonstrate why a good amp is so highly prized by audiophiles especially when the loudspeaker is demanding of it.

CD: Casting Crowns – Casting Crowns
For some additional two-channel listening I fed the Rotel some tracks from Casting Crowns’ self-titled album. Track 10 “Your Love is Extravagant” is a beautiful track and one of the cleanest tunes on the album. The bass line and gentle guitar picking were presented with much detail and imaged well within the soundstage. I played with much more in terms of two-channel but the bottom line is that a dedicated high-quality amplifier will breath new life into your CD collection if you’re coming from a mid-priced receiver or other lower-quality amplifier.

Movies

For subjective 5.1 testing we left the realm of critical listening and entered the “raw power” zone. I cranked up several scenes from The Empire Strikes Back, Shrek, Farscape Season 4, and Lord of the Rings: The Return of the King. IN particular, I tried to find scenes that utilized the main and surround channels without necessarily driving the subwoofer too hard – after all, we’re evaluating the Rotel, not my subwoofer’s amp. I found that (in order of appearance) starship flybys, dragon battles, close-quarter combat scenes, and large hoards of attacking orcs could be played back at floor-shaking levels while sounding pristine on Reference System 3. It was exciting to be able to have so much dynamic range and headroom, and not have to encounter audible distortion or situations where the system was overdriven. The RMB-1095 certainly does not disappoint and provides ample clean power with room to spare – a trait shared by many THX Ultra and Ultra 2 products due to the nature of the certification process.

Conclusion

Lack of distortion and tight control over my low impedance 4-ohm RBH Sound 1266-LSEs really made a difference and quickly showed off the advantages of a high-quality amplifier.

It should be noted when considering an amplifier upgrade from a receiver there are several dependent variable to consider:

• Loudspeaker Impedance – speakers with dips below 4 ohms tend to be driven better by a high quality amp such as the Rotel.
• Loudspeaker Efficiency – speakers with lower than 87dB SPL @ 1 meter tend to benefit from a dedicated power amp
• Room Size – rooms larger than 2000cu ft require solid amplification which can sometimes exceed capabilities of mid-priced receivers
• Room Acoustics – depending on the liveliness of the room, a well damped room can eat amplifier power
• Listening Preferences – if you like to blast music and movies to THX or even ear bleeding levels, depending on the variables above a powerful amp like this Rotel can certainly make the difference.
• Whether or not you apply bass management to your Loudspeakers and utilize dedicated powered subwoofer(s) – most of the power in a home theater system is in the bass. When utilizing full range speakers, a robust amplifier will deliver more control and drive to the speakers.

There’s really no magic going on, you’re simply getting what you pay for – good clean power. By my calculations, the 5-channel Rotel costs just over $26/pound. For that price I’d say skip the Maine lobster and order up a Rotel RMB-1095.