computer audio question

With cd players you can change the sound by changing cdp.
With harddrive setup, how do you? That is one problem I found.
I have never changed DAC but I am not sure it will make a big difference? Mine sounded kind of like it came from a computer.
(b.c. dac2)
Different DACs can sound very different. How different will depend on what DAC you are using and what replacement you are getting.

Different software players can sound different too and in some cases, they sound more different from one another than different DACs do.
Changing a DAC is akin to changing a cartridge. As Sidssp implied, do not discount the transport aspects too. There has been great strides made in that arena through the use of computers as the digital transport mechanism including the player software and file types.
There are processors with freon cooling instead of fan which are much more quiet than fan cooled ones. That could be the tweak becides DAC, but as previously mentioned DAC makes the largest difference.
There's been much progress in DAC and DAC chips design since The Bel Canto DAC 2 came out almost 10 years ago.

That said, Your most cost-effective upgrade at this point could be to add something like the M2Tech Hiface USB/SPDIF converter and output your computer's bitstream data through a USB port. This isolates your computer RFI/EMI from the DAC, helps control jitter, and has other benefits which all should help your source sound more musical.

As others noted above, it all begins with a good lossless audio file being output from one of many good software packages such as Foobar or JRiver for PC, or ITunes for the Mac.
The DAC should make a noticeable difference similar to changing phono carts as noted or even simialr to changing players with built in dacs.. If not, then the system may just not be very resolving or revealing to start.
Im using a BC DAC2 ,Imac ,Itunes,with great results!How do you have things
hooked up?
(This was with waveterminal u24,macbook.)

What I am asking is, what specs make a great setup?
Ie. DAC2 supposedly had great jitter rejection. It sounded like improved CD (vs vinyl)
The most important thing in ANY digital audio system, whether CD or computer is the source jitter. Make sure you have the lowest jitter source first. This means put your money into the best clock you can (inside the device), whether its a CD player or USB converter or USB DAC. The jitter of this clock is a function of the clock itsef as well as the power system powering the clock.

Second, DAC's can sound very different. I recommend avoiding hardware upsamplers so that you can hear the benefits of the low-jitter source you have painstakingly selected. Otherwise, all you are hearing is the jitter from the internal upsampling clock in the DAC. Few of these are decent IME, and I have modded a lot of DACs over the last 10 years, more than any other modder in the business.

Try to get a DAC with a discrete analog output stage with good drive and a volume control that allows you to drive amps directly. Avoiding a preamp can be a huge win in SQ.

Dont necessarily bite on the latest technology, such as 32/184 etc.. There are not tracks available, and even 10 years from now when they are, your favorite music will not be in this format. Also, the lastest DAC chip is not necessarily the best sounding. They may have slightly more detail rendered, but they also have the fatigue factor to go with it. some of the new technologies for D/A are not musicl IMO. Better to go with known great sounding chips, such as PCM1704, PCM179X, TDA1543, Analog devices and Some Wolfson chips.

Steve N.
Empirical Audio
Dear Steve N.-Excellent points. Newer NOT always better. How do you like the Burr Brown PCM 2702E?
"Newer NOT always better"
Okay, but in the Bel Canto series cited by the OP, newer series DACs are definitely better in just about every meaningful respect, except perhaps cost.

"Better to go with known great sounding chips, such as PCM1704, PCM179X"
Interesting that Bel Canto's DAC3 represents an upgrade to the PCM1792.
As a wise man once told me, in audio... "everything affects everything".

We have found that it is very easy to improve the sound quality with better cables (USB, Firewire, power cords, and of course interconnects from the DAC to the pre-amp), the DAC itself, music player software, and even the software that you use to rip the CD.

The old addage about "garbage in/garbage out" is certainly true with digital music servers. What goes into the DAC makes a huge impact on the sound quality that comes out. Certainly the better the DAC, the better the sound, but price is not always the best yardstick to measure performance by. We have heard several DACs that don't sound all that great, but carry a high price tag and we have also heard some that are very reasonably priced and sound great.

Steve Nugent makes some excellent points (as well as some excellent products) about jitter, digital volume controls, and using the right DAC chip, but the simple answer to your question is that better sound starts with the computer that is connected to your DAC.

Here are a few do's and don'ts.

Don't use USB for both the external hard drive and the DAC.
Don't use an internal SATA or an external eSATA drive to store your music on.
Do use a Firewire 800 external Hard Drive with an Oxford 93x or 94x chipset for music storage.
Do use a cut power Firewire cable.
Do use an asynchronous USB DAC and set the clock to the DAC.
Do use an SSD as the boot drive in your computer.
Do turn off or kill any and all processes that aren't absolutely necessary.
Don't use iTunes for ripping!!!
Do use a good quality USB cable from the computer to the DAC.
Do put at least 4 GB of RAM in your computer.

One of the biggest things that we have found is that when you get rid of the noise introduced by the switching power supplies (inside and outside the computer), the sound quality improves dramatically.

Kevin Burke
Mach2 Music

A network player like Squeezebox Touch connected via wireless G performs extremely well in all regards and helps effectively isolate your system from the music server host computer and associated noise issues. A very cost effective and simple solution.
"How do you like the Burr Brown PCM 2702E"

Have not heard it yet. I know what I dont like: the AKM chips.

Steve N.
Empirical Audio
"Okay, but in the Bel Canto series cited by the OP, newer series DACs are definitely better in just about every meaningful respect, except perhaps cost."

Read the upcoming review in TAS on this.

Steve N.
Empirical Audio
"A network player like Squeezebox Touch connected via wireless G performs extremely well in all regards"

A lot of audiophiles reclock the SB Touch, SB2, Duet and Transporter. Again, it's the clock that is most important. However the Touch is the best of the lot in stock form.

Steve N.
Empirical Audio
Not sure what recent upsampling DACs Steve is skeptical about, but IME the relatively new ESS 9018 Sabre chip(when implemented in dual mono with well-executed discrete dc regulation) is an advance over any commercial offer that I've heard. Detailed, smooth, delivering a payload of life-like energy without fatigue. Unfortunately any DAC chip is no better than the sum of its surrounding clock, PS, and analog stage, so YMMV.

How is a Touch reclocked? I have one and I'm figuring out the best way to improve it's sound. It's stock, with std settings, and using its DAC too.