Has anyone try the Benchmark DAC1 Preamp?

I know somebody who added an old Krell PAM-1 to his Benchmark DAC1 and said that it made an improvement.

The integration of a preamp and DAC makes no sense to me. I would rather have the DAC integrated with the transport. Reasons:

- analog signals do not benefit as much from short signal paths anywhere near as much as digital signals
- every interface you add in a digital system increases jitter
- putting a preamp in a DAC means that even more of your analog signal is exposed to high freq digital noise
- digital preamps are mostly lousy and should be avoided
- analog preamps are better anyway, and you are better off having a seperate analog preamp than to have it built into the DAC for so many reasons. If you are going to have an analog volume control - why have it built into the DAC?

I can't think of any good reasons to have a preamp built into the DAC. If you want a DAC, get a DAC ... but don't think that a built-in preamp in a DAC will be superior to a standalone pre. In almost all cases the standalone pre will be superior.

If you're referring to the DAC1 Pre, why not just eliminate your preamp from the system and go straight into the amp (if you have separates)?
regards, David

Ive lived with the Benchmark dac 1 as a pre-amp balanced driving a Jeff Rowland Digital amp. It actually sounded real good!

Amfbius there made some very solid points and agree with his conventional wisdom as well.

I have the Cary SLP98 which does do a wonderful job driving my amps.

It was for kicks that I actually try my DAC1 directly driving a pair of ASL 845 SET amps to my innersounds. I was delightfully surprise the outcome. The DAC1 gave more detail and immediacy to the sound and the big 845 tubes of the SET amp still allow the music to have body enough.

This experiment has lasted a couple of weeks now and now I have my Cary SLP driving my nuforce amps to warm those up with my vmps speakers.

So when I saw Benchmark actually is making a Pre-amp DAC, I'm hoping it's more than just a DAC with a volume control. Hopefully would do a better job as a preamp than the DAC1. That's why I started this post to see if anyone else has experimented.

I have been impress with how the DAC1 mix so well with my SET amp...

I have not tried the new dac1 preamp but I do use my benchmark dac1 to control the volumne. I have a adcom 5 disk cd player I use as a transport and the dac1 to my pass labs aleph 3 and my velodyne hgs12 subwoofer. I have totem model 1 for my for monitors. The sound is incredible! a very simple 2 channel setup. I do not need anything else, I only listen to xrcd and cd's. mostly jazz and clasical and guitar and a little rock. I have a music/ office room. the dac1 preamp will be more flexible when having different components but I love my dac1, I also have done the cone mods to the dac1

I've had the DAC-1 Pre for a couple of weeks now and IMHO it sounds excellent. Previously I had the regular DAC1 and either ran it straight to my power amp, or through my Bryston BP25. The DAC 1 Pre sounds better than either of those combinations. Needless to say, my BP25 will be on the market shortly.

Cldinsmore, was your DAC1 the DAC1USB?

I asked BenchMark, the difference between DAC1USB and DAC1PRE, other than the extra input, is the premium connectors and more use of LM4562.

Since I don't need the extra analog input, I was thinking that the DAC1USB might be all I need.

No. Mine did not have USB.

Also...It sounds like Amfibius is saying the DAC1 Pre is a digital preamp. The preamp in the DAC1 Pre is analog and so is the volume control. I'm also not sure what he means when he says "every interface you add in a digital system increases jitter." The DAC1 Pre is not adding any additional interfaces. Even if it did, the DAC1 is immune to jitter due to the Ultra Lock system. I would also think that analog signals do benefit from short signal paths more so than digital. Digital signals being '0s' and '1s' are much less prone to contamination. As far as exposing the analog signal to digital noise...the DAC1 Pre is dead quiet and has an incredible S/N ratio.

Cldinsmore I don't know what type of preamp the Benchmark DAC1 PRE is because the literature in their website does not say. Consequently I did not say if the DAC1 PRE was digital or analogue. If you say it is analogue, then you must be better informed than me.

As for "adding an additional interface", what I mean is the connection between transport and DAC. In a one box CD player the connection between transport and DAC is short, and the impedance is matched. With ANY outboard DAC, you have: output jack, cable, input jack. The length and impedance of the cable is not known by the designer, and each cable/jack interface is a major source of jitter.

"Immune to jitter from the data lock system" ... either someone has been reading too much marketing material or Benchmark is able to offer something that even Meitner can not do :)

I would also disagree with your contention that 0's and 1's are less prone to contamination than analog signal. Remember that a 16 bit PCM digital transmission is a square wave transmitted at 1 MHz (by Fourier analysis even higher than this - thanks to H3, H5, H7, and so on). Digital signal is exquisitely sensitive to impedance mismatch. Analogue signal is "only" 20Hz-22kHz. Which do you think would be more prone to degradation?

Thanks for the clarification Amfibius.

As far as the issue of transmission of analog and digital signals go I am certainly no expert. I was just reiterating what I've read...most notably David Rich (EE) and Peter Azel (Audio Critic). Also, if the cable interface is so critical why doesn't Benchmark mention anything on the subject? I have spoken to them regarding cables and they said any decent coax cable will do the job. I have also used a couple different cables and they sounded identical to me. Could you direct somewhere where I might read something on what you describe?

As far as the jitter issue goes, again I am no expert. I'm just going by all the reviews of the Benchmark I have read. They all say that the unit is remarably free from jitter and the unit has been extensively reviewed.

Here is an excerpt from the Audio Critic on the subject:

"Perhaps the most sensitive distortion/noise test is what I used to call the Rob Watts Test (named after Rob Watts, a U.K. engineer), consisting of the FFT spectrum of a dithered 1 kHz tone at –60 dBFS. This is shown for one channel of the DAC1 in Fig. 2. The largest blip sticking out of a bin-by-bin noise floor of –146 dB is no taller than –134 dB. (Is that clean enough for you?)"

They go on to say, "A word about jitter. Some high-end reviewers flap their wings very vigorously on the subject, but as Bob Adams pointed out more than ten years ago in the abovementioned article, there is no reason to single out distortion components caused by jitter as distinct from those caused by other circuit mechanisms. Distortion is distortion, no matter where it comes from, and the tests above cover that ground in sufficient detail. To isolate and measure jitter, one would have to remove the cover and go inside the Benchmark DAC1, because it doesn’t have a digital output (nor does it need one). The instruction manual goes into great detail about jitter, with four different graphs to prove the DAC1’s immunity to it. Just for the hell of it, without much hope of significant results, I ran a hi-rez FFT of a full-scale 20 kHz tone to see if there were any noise sidebands in its vicinity that would indirectly indicate the presence of jitter. As Fig. 7 shows, there weren’t any, at least not under the conditions of my quickie test. And that’s all, folks."

Sure Cldinsmore - here is a good link. http://www.jitter.de/english/engc_navfr.html