Just got the PS Audio Perfectwav DAC -- Amazing

The digital volume controls on the squeezebox work by changing the bits. In other words, there is some digital re-sculpting of the signal, and it's lossy.

Supposedly, it gets worse as you attenuate more and more, and I don't know at what level it is "still OK".

I don't know if the Transporter does the same thing, but I would be surprised if it didn't.

Hence the standard recommendation to let some other device do the volume attenuation. Yes, those are lossy too--but in an analog way, and that's usually better by comparison.

Before passing judgement on the DACs, you could insert a preamp--any preamp, probably!--between the DACs and the amp and then do some a/b testing. The difference you have been hearing between the two units may go away, or become a different difference; hopefully, in both cases, you will hear them play better.

I don't know why you guys are not talking about this, but I think that the real issue with using the DAC to attenuate the volume is whether that is achieved by analog or digital methods.

If it is done digitally, then you are definitely losing original bits from the songs. Lossy. Think mp3. No surprise if you lose "3D", and you're probably losing something in the 2D and 1D and 4D and 23D as well, whatever that means. Lossy. Worse with more and more attenuation, and if you're bringing it down from 100 to 60ish then you can forget about hifi.

If the attenuation is done via analog, then of course it depends on how well it is done. Now that is precisely what a preamp is suppose to do! A good one should do it well, and if the DAC outperforms it then we are talking about one hell of a great DAC (or one lousy pair of interconnect cables).

I know that the squeezebox attenuates by digital manipulation; I'm pretty sure that the Transporter does the same thing. This thread will shed some light on this,

http://forums.slimdevices.com/showthread.php?t=30916

Basically, you want to listen to the slimdevice gadgets at maximum volume and attenuate with something else; or use them to get the 1s and 0s into whatever DAC you like, and then go through there to, once again, a preamp.

Anything else and you're asking for lossy data. Mp3s, maybe nice mp3s, but still mp3s. The whole point of flac gets tossed into the bitbucket.

I have no idea what the PS Audio dac does to achieve this. If it trumps a preamp, then it's a better preamp than that preamp. If it trumps all preamps, then it's a hell of a preamp (well, except for its lack of non-digital inputs!). But if it does it digitally, then it's lossy. The fact that their web site does not mention this issue is not encouraging,

http://www.psaudio.com/ps/products/description/perfectwave-dac?cat=

since it is a clear big selling point and they should be explicit on the method (sadly, the logitech transporter site does not mention it either). For $3k, I would expect one hell of a volume knob...

Thanks for the links, Levy03. I am going to check them out.

If I come to the conclusion that I have to eat a little crow, I'll be sure to do so. It is highly nutritious, according to Dr. Friedrich Nietzche. :)

I just went through the remarkably long description of the PW DAC on the PS Audio web site. They do not even mention how they attenuate the volume, which must mean that they do not think it is a very important issue.

They do go on and on about the various digital filters that they put in this gadget, though...

The digital volume control seems like such a deal breaker.

If you pay something in the neighborhood of $3k, for the sake of hi-fi, only to watch the accuracy of the system go away dramatically with a digital volume knob, it seems a shame.

I think that the $400 DacMagic paired with a midfi preamp (altogether, less than $1k) would sound better than a $3k DAC that uses a digital volume knob.

2chnlben, do your homework on how a digital volume control gets the job done.

On the other hand, if you cannot tell the difference between an mp3 version of a song and the version on the CD, then you might be OK with it...

Ok, the digital volume control will usually alter the 0s and 1s as they enter the DAC. So what the DAC processes and turns into sound is quite different from what is on the CD or hard drive.

It is not a small matter. It is "as bad" as it gets. Ok, maybe not as bad as blowing an output tube, but people, we have standards here! Think of the little audiophiles!

Thanks, Richard, for the tip about the Berkeley alpha dac! It's good to learn something new. I'll probably never be able to afford one, but that does not stop me from drooling a little bit after it. :) I am very curious now about just how they get this little task done, because it's a bit of a math problem that needs to be solved real-time, oh, 44,000 times per second! :0

What makes me suspicious about the PS Audio gadget is that they went on and on and on about far less relevant stuff in their gadget, but they never talked about this digital volume control problem. When someone ducks the mention of a difficult issue that has stopped those that came before him, the safe thing to assume is that they are ducking the issue and pretending it is not a problem.

I asked PS Audio about this and did not get a response. Maybe they'll address it someday.