Connecting Laptop to Benchmark DAC

There is only one way to connect it to the benchmark DAC1 -- digital out from your laptop to the DAC, if your laptop's soundcard dosn't have digital output, then you will need to buy a external soundcard that can pass thru the digital signal.

That one's easy: When the output is bit perfect. You don't even need extra low jitter, given the DAC1 does some buffering anyway; bit perfect alone will do just fine. Can't give you any specific recommendation, I'm not into external audio (poor notebook is gathering dust in parts, nicely fried mo/bo).

This is becuase most people don't realize S/PDIF sends both analog and digital signals. The digital component contains the amplitude of the sound wave at each sampling point. The analog component contains clock signals to signify the DAC to perform D/A conversion at specific time points. The clock signal can go too fast or too slow, and this timing error is called jitter.

Many DACs have circuits for minimizing the distortion caused by incoming jitter. Hi-end DACs are generally better at minimizing jitter, and hi-end transports generally has less jitter in its output. A few DACs can completely reject jitter and is therefore jitter-immune and transport-independent in terms of sound quality. Benchmark Dac1 is one of them.

Of course, if the transport sends out incorrect bits, every DAC will suffer. This normally is not an issue with decent CD or DVD players. But PCs running windows XP and some other microsoft OS by default sends bit-imperfect signals because kmixer scres it up. This is a complicated issue and I don't fully know the details. But I know M-audio Transit USB and Foobar is a good solution (for me). Using Foobar in ASIO mode (to bypass Windows kmixer), Transit USB will output bit-perfect signal from any computer with USB. Plus, Transit it self sounds decent as a DAC (comparable to ~$200 CDP) and headphone amplifier (for easy-to-drive phones like PX100). Its ADC is a bonus but I have never used it. Transit USB is around $80 and functions like a Swiss-Army Officer's Knife.

The Benchmark DAC1 is supposed to be immune to jitter so it shouldn't be high priority to get the best quality digital output from a soundcard/transport.

But there really isn't a super high quality external "normal" soundcard for a laptop. There are "systems" like a PCMCIA adaptor which plugs into another large device type of soundcard. Or you can go with something like Apogee Big Ben which is an external clock. WIth those you are easily >$1000.

It's also not esoteric or a matter of preference. Lower jitter = better sound quality.

The Transit outputs PCM. It would only output AC3 if you're playing a DVD and have the digital passthrough feature enabled in your DVD playback software.

Yes you can use any optical output. Just make sure it's bit perfect.

Exactly.
Used Transit with Benchmark DAC1, no problem.

BTW, Benchmark DAC1 basically ignores the clock component of incoming S/PDIF signal. DAC1's internal D/A conversion is therefore not guided by the transport's master clock and jitter is a non-issue. Look at DAC1's manual, available on-line, to see how 1000 ft cheap cable and severe, injected jitter do not cause any jitter-induced side peak. When a DAC completely ignore the clock signal from S/PDIF, it is not affected by the jitter in that clock signal. This is in fact a reasonable approach, because the DAC has its own clock IC as well and does not really need an external clock to tell it when to do D/A conversion. With Benchmark DAC1, just forget about source jitter and certainly don't spend extra money to adress jitter--it's already addressed to the max.