NAD Masters Series M15 THX Ultra2 AV Surround Sound Preamplifier M25 THX Ultra2 7-channel Power Amplifier:
Page 4 With regard to the multichannel analog input, recall that it's a pass-through, with its analog input remaining in analog form all the way to the output. There is no processing or bass management of any sort. The only things in its signal path are the master Volume control and gain-free output buffers. While these may have subtle effects, the sound quality you hear from it will be dominated by the rest of the system, particularly the source feeding it. I heard nothing negative from this analog input that could clearly be attributed to the M15 itself. I'll have more to say about the M15's multichannel analog inputs in a separate review of the NAD M55 universal DVD/CD player, coming soon.

Movies
All of the audio soundtracks for the HD DVD and Blu-ray titles used here, including those reviewed by me in UAV's Movie Room, were auditioned from the disc players' digital outputs. This bypassed the full advantages of such advanced audio codecs as Dolby Digital Plus, Dolby TrueHD, DTS-HD Master Audio, and 5.1-channel uncompressed PCM. These are available only via the multichannel PCM riding on HDMI 1.1 or later, or from the players' multichannel analog outputs. But as I mentioned earlier, the M15 AV surround preamp cannot extract the audio on the HDMI cable. And using the analog outputs of the HD DVD and Blu-ray players into the multichannel inputs of the M15 would include the D/A converters in the players—which are not under review here—and bypass the D/A converters in the M15, which are.

Whether the program material is HD DVD from the Toshiba HD-A1, Blu-ray from the Panasonic DMP-BD10 Blu-ray player, or conventional DVDs from the NAD M55 universal player, the NAD Masters system sounds sweet, detailed, and handles extreme dynamics with ease.

The opening title sequence of Serenity on HD DVD (chapter 3) starts off accompanied by some of the most lush string playing this side of a good audiophile recording, and the richness and full-bodied timbre of the NAD M15 and M25 do it full justice. But a few seconds later the audio tracks explode as the rocket engines kick in and the music simultaneously soars to a huge crescendo. I only became aware of a very slight sense of strain in this passage when I listened to it again later using Anthem's Statement P5 power amplifier, which is nearly twice as powerful and more than twice as expensive per channel.

I watched and listened to dozens of other movies with the Masters Series gear and was never disappointed by what I heard. With standard definition DVDs, the M55 more than held up its share of the bargain. And with HD DVD and Blu-ray discs it was through the NADs that I first began to fully appreciate the improved audio quality available from those formats—even as heard from the players' standard digital coaxial output.

Rather than ramble on here with more examples, I'll simply refer you to UAV's Movie Room. All the HD DVD and Blu-ray discs I reviewed there, from the Superman titles to The Mummy were watched and listened to with the NAD Masters Series M15 and M25, and the rest of the setup was largely the same as that listed in my "Review System," below.

The NAD package never bit back on soundtracks and never sounded hard or excessively aggressive. One observation remains a puzzle, however. Recall that in my discussion above of the system's music reproduction, I referred to the system's sparkling, immediate, but not overly bright sound. Yet on movies I sometimes felt that while the system was always eminently listenable, some soundtracks seemed just a shade too sweet and laid back, lacking a bit of speed and incisiveness. I checked this against the Anthem Statement P5, both amps driven by the M15 surround preamp. Overall, the harmonic structure of the M25 lacked a little air and sparkle compared to the more expensive P5, but gives up nothing with respect to sheer listenability. The NADs work in concert with, and enhance, the overall AV experience rather than dominating it.

If you have to have a puzzle like that, I'd say that a system that sounds sparkling and detailed on music and a little softer on movie soundtracks might be unusual, but hardly unwelcome.

Conclusion
My only serious issues with the two NAD masters Series products on review here involve the video switching on the M15. The lack of audio over HDMI is bothersome, and buyers with important composite and S-Video sources will also find the video switching of those modes problematic.

But I can't deny that I had a great time with the NAD Masters Series M15 and M25. While I could go on and on about their sound quality, let me close this epic-length review by noting that I had a hard time pulling myself away from my sessions with these fine products. I'd be listening to them now if I didn't have to write this report!

Highs (M15 and M25)
Superb sound
Outstanding build quality
Exceptional Value

Lows
No audio on HDMI (M15)
Cross-conversion of composite and S-Video inputs to component clips blacks below 12.5IRE (M15)
Front panel displays/lights cannot be dimmed
Fan noise (M25)