Power Amplifiers

Rotel RMB-1575 Five-Channel Class D Power Amplifier


In Use


The power supply in any amplifier is crucial to sound quality. As this amp utilizes a shared power supply configuration I wanted to test this amp with multi-channel music to really tax the power supply. As well, Class D amplifiers in the past have been know to have some high-frequency artifacts so the extended high frequency response found in SACD and DVD-Audio discs make them perfect for testing class-d amps.

Rotel RMB-1575

For my first listening session I used the SACD version of Dark Side of the Moon. One of the finest examples of what the SACD format is capable of outside of classical music. The clocks chiming at the beginning of Time were clean, clear and showed no distortion. Next was Great Gig In The Sky – Claire Torry's vocal solo was consistently beautiful and melodic at all volumes with no noticeable distortion.

Rotel RMB-1575

My next session was with the Frank Zappa live compilation Halloween, recorded over five days in NYC around Halloween 1978. Dweezil Zappa and Joe Chiccarelli have done an admirable job recreating the live shows and the DVD-A format is ideal for Franks live music. The mix puts you right in the audience, the sound is astounding with the band up front and you are immersed in the crowd. The recording is amazingly clean for a live recording from the 70's. There is great separation of the instruments and band members. The RMB-1575 never failed to provide clean sound even at (close to) live SPL levels.

Rotel RMB-1575

One of the more dynamic and demanding discs I have, especially for high-frequencies is The Melvin's A Senile Animal. This album finds the Melvins with two drummers and is an all out percussive assault. Percussion separation is what I am listening for with this album, there are layers of heavy distorted guitar, solid bass playing and too many drums to count. With the RMB-1575 the cymbals, high-hats and gongs (yes gongs plural) never muddled together and were always crisp. Lower quality amplifiers just cannot resolve the detail present in this album when pushed too hard. The Rotel had no problem presenting all the intricacies contained within this heavy-rock tour de force. Every song was easily reproduced with no shortage of dynamics. Of course this is an easier test than the previous albums as the amplifier only had to power two channels. This album proved that this amplifiers high-frequency response is excellent.


Rotel RMB-1575

As this is a muti-channel amplifier it will see more movies than music for most people. When I really want a surround work-out I use the funny and intense Stephen Chow epic Kung Fu Hustle. There are many scenes that test the systems acoustic balance with flying axes, swift punches and unreal bass. An abundance of immersive special effects and slow motion fight scenes put you right in the middle. After the end of the movie I was unable to detect any excessive heat from the amplifier.

For Comparison

Rotel RMB-1575

I had two other amplifiers on hand to directly compare to. The internal amplifiers in my Denon 4308 receiver plus a 10series Rotel RMB-1085, review here. Compared to the Denon the Rotel was slightly better in dynamics and soundstage at moderate to loud volumes and some-what cleaner at very loud volumes with DVD playback. At softer volumes I found the Denon had more detail and was more engaging. Compared to the 10 series amp the difference was slight, with the RMB-1575 having better bass control and mid-bass clarity. Given that my speakers are relatively easy to drive I was not surprised that the difference was minimal.