I wanted to post some thoughts, and questions and experiences I have with my Rotel 1572. As you might know, I got mine back in October and I have been wresting with the audio clipping problem. (See above and in the Rotel owners thread)
I read Kal Rubinson's review with great interest last week in the March issue of Stereophile. I was disappointed he didn't comment on the clipping issue. And I am curious if he is aware of it and experienced it.
I have spoken to the dealer I bought mine from and they've experienced the same problem on their unit and have been talking to Mr. Sheehan at Rotel. I understand they are aware and working on a fix.
What was bugging me, aside from the annoyance of every track clipping, is that some people don't seem to have this issue. Yet there are many reports from others who do. And from other brands too. Mr. Rubinson didn't report it, so perhaps he's not experiencing it.
I thought I'd try an experiment because I wondered why sometimes I didn't hear the clipping and other times I did. I used the Coax connection from my Blu Ray player to the Rotel's CD input for Coax to avoid the HDMI. At first I thought solved it, but then I heard other CD's with clipping! So out of frustration, I tried to do a direct analog out from the BD player to the analog input on the Rotel. That of course solved it for sure. But I didn't like the sound. The BD player is a Sony from 2008.
So I tried a test with the optical toslink from my Sony BD player to test that theory. It is hooked up to the Optical-in on the Rotel and I programed to default to PCM 2 channel.
At first I thought this licked it. No clipping on the CD I played. I could not believe my ears. So I tried a few others. No clipping until I tried another CD and then it clipped!
I soon discovered that a consistent repeatable result would occur where the first track will clip, but the rest of the album will not if left to play undisturbed. But if I skip a track or select a track, that track starts with a clip. And the rest of the disc plays fine.
And then I found other CD's that clip every track. Just like with the HDMI connection. So I tested that theory and played back the same discs that only clipped the first track and plays the rest fine with the HDMI setting. The Optical setting is acting like the HDMI setting.
This lead me to a theory that perhaps some CD's have a digital signal built-in or some such thing so the Rotel cannot sense a break in the track. And when I told a buddy about my theory, he said that some CD's include something called a pre-gap. You can see if a CD has this if you see on the player's digital counter a negative number as it counts down to the next track. I did notice that most CD's I have with the pre-gap didn't clip. But I guess there is no pre-gap on the first track, so it clips.
I also wondered if each record company used different encoding methods. So here's where the methodical science comes in. I noted a few random CD's I pulled from my collection and played them to look for the pre-gap and for the clipping. Here's my results:
A&M Records Inc.
-Sheryl Crow, The Globe Sessions, no obvious clipping.
-The Beatles Remastered Mono Box Rubber Soul. First Track clips. Following tracks do not clip.
-The Beatles Remastered Stereo Past Masters. First track clips, following tracks do not clip.
-The Beatles Remastered Stereo Abbey Road. First track clips, following tracks do not clip.
-Sarah McLaughlin, Afterglow, Fumbling Towards Ecstacy. No clipping.
-Kings of Convenience, Quiet is the New Loud. No clipping.
-Cold Play, A Rush of Blood to the Head and Parachutes. No clipping.
-The Byrds, Best of, all tracks clip
-The Dave Brubeck Quartet, Time Out (2009 remaster Sony Music) no clipping.
-Miles Davis, Kind of Blue (2009 remaster Sony Music) there is clipping. I do hear a click or pop between tracks. If I select a track directly, there is clipping.
-The Cure, Galore the singles. Has countdown, but tracks still clip and start at 1 second in.
-Steely Dan, Aja. Has countdown, but clips each song. Faint click heard between tracks.
-Donald Fagan, The Nightfly. First track clips, Other tracks do not appear to clip.
So does Aritsa, Capitol Records and EMI do something different? It's clear to me why I didn't notice any clipping when I auditioned the Rotel at the dealer. I used those 3 albums by Coldplay, Sarah McLaughlin and Kings Of Convenience.
One other thing I did. My Sony BD player settings have to be set for audio out preference. So I set it to Optical preference during the test. I wanted to be sure the audio wasn't going through HDMI, I also tried a very old Sony CD player that had optical out to be extra sure no audio was going through HDMI and it gave the same results.
Another observation. Not surprising, the DAC from the Sony BD player I imagined was okay. And it was alright when I played analog out from that player to the Rotel. But when I went back to the optical out from the BD player and used the DAC in the Rotel, it sounded sweet! So this led to the question: Is the Oppo 95 worth it for me? I researched it and it's only really good reason to have is the built-in DAC and the analog outs. If I use the analog outs, then I don't use the DAC I paid for in the Rotel. It would only be used for movies.
When I heard how good the music sounded from the Rotel's DAC, I figured with my modest system of Rotel and B&W 805 speakers, I would be happy with the Oppo 93 via HDMI and optical connections. And I understand I could also use the analog 7.1 outs from the 93 and down mix to stereo.
I have been contemplating an Oppo 93 or 95 for some time. Everyone raves about their musical ability. And I found one thread on another forum where a user solved his clipping problem by using the optical from the Oppo 93 to his Rotel 1572. If that is true, then I would be amazed! I suspect its really about how the CD's are encoded that is confusing the Rotel and other pre-amps. So the HDMI software has to be re-written to allow for the gaps or to turn on the digital setting you want automatically before the CD plays.
Well, that's it for now. I plan to do more testing to see if I can get around the clipping. Not sure buying an Oppo will solve it! I am still waiting for Rotel for the proper fix and I still have confidence they will. I look forward to any comments from any one.