Where/How can I further improve PC audio quality?

latest DAC with asynchronous inputs. Asynchronous mode is technically most advanced for re-timing and re-clocking. It will deliver the best sound possible. I purchased the ZDAC for $300 last year and the different is huge and never look back.
May be you can further improve Audio quality with high end brand name, however I only believe in technology not pricing.

I assume that you're using the "on board" sound from your computer. That's a big problem. As stated, A USB DAC, without any up sampling/down sampling, will go a long way to improve sound.

Is it that the sound from the computer is not equal to that from the 840c playing CDs and you are happy with the 840c when doing so? One issue is that you are streaming a lower resolution file from Spotify, therefore the signal from the computer is not as good as that from the transport. That said, you might benefit from sending the digital signal from computer via USB and using a USB/SPDIF converter and going coax to the 840c. This way you take advantage of the 840c’s DAC and pay only for the digital conversion device.

I thank all of you for your input. I am not using an "on board" connection, I'm using a PCI card. At this time I am using the highest resolution the card can deliver, I'm going to try experimenting by setting the card to minimum, i.e. 16 bit 44.1Khz and letting the CDP do all of the upsampling work.

spotify is MP3. Anything will be better.

re Spotify Premium (from Wikipedia, Spotify entry)...

"Spotify software is proprietary and uses digital rights management (DRM) to prevent unauthorised use. Users who agree to Spotify's Terms and conditions agree to not reverse engineer the application.[87]

Audio streams are in the Vorbis format at q5 (ca. 160 kbit/s),[88] or optional q9 (ca. 320 kbit/s)[89] for Premium subscribers. Spotify has a median playback latency of 265 ms. It amounts to 390 ms without local cache usage.[90]"

(from Wikipedia Vorbis entry)

Vorbis had been shown to perform significantly better than many other lossy audio formats in the past in that it produced smaller files at equivalent or higher quality while retaining computational complexity comparable to other MDCT formats such as AAC or Windows Media Audio.[28][29] However, as of 2014, not many further significant tests had been made.

Listening tests have attempted to find the best quality lossy audio codecs at certain bitrates. Some conclusions made by listening tests:

Low bitrate (fewer than 64 kbit/s): the most recent (2007) public multiformat test at 48 kbit/s showed that aoTuV Vorbis had a better quality than WMA and LC-AAC, the same quality as WMA Professional, and a lower quality than HE-AAC.[30]

Mid to low bitrates (fewer than 128 kbit/s down to 64 kbit/s): private tests in 2005 at 80 kbit/s and 96 kbit/s showed that aoTuV Vorbis had a better quality than other lossy audio formats (LC-AAC, HE-AAC, MP3, MPC, WMA).[31][32]
High bitrates (greater than 128 kbit/s): most people do not hear significant differences. However, trained listeners can often hear significant differences between codecs at identical bitrates, and aoTuV Vorbis performed better than LC-AAC, MP3, and MPC.[33]

I have no business interest in Spotify but am a satisfied Premium subscriber.

Download the sampler form HRTracks so you can see if you can hear the difference between low bitrate (Spotify and MP3) and high bitrate music. Its a world of difference on any reasonably resolving system.

I think Mesch has given you very good advice. In digital playback the clock is of paramount importance to reduce jitter. A computer is an electrically noisy environment and generally a bad one for a precision clock. A USB-to-S/PDIF converter with asynch USB (probably they all are) will have a precision clock housed in a more conducive environment and the asynch USB will have the computer clock slaved to that of the converter.

This will likely be the biggest bang for buck improvement. Going to higher resolution audio might be second. If you were to go with CD quality then the choice of playback software would be significant too, and the computer itself.

We are suggesting reclocking MP3's? to get to what? an MP4?

To me, at this time, my Spotify Premium subscription more than satisfies. I'm delighted with their solution to streaming audio and the simple to use GUI. The sound quality I have achieved so far is close to CD playback, however, I'm attemting to "tweak" out the best it can offer. The solution I'm going to try is a better card that has only digital outputs and claims to support asynch for improved clocking and a claimed low jitter output.

Thanks all again for your help!

The advice for a good USB converter is sound, however it requires that you jump through some hoops for the computer.

Rather than doing this, Just add a Synchro-Mesh reclocker to the digital feed from the PCI card and drive the DAC with the SM. Reducing jitter is what is needed and the SM will do this for you. It will even improve MP3. Relocating the clock that is used for master clock from the computer to a more controlled environment is the ticket. The SM does this for you. you can also upgrade the power supply to a Dynamo, which makes an even bigger difference. The SM can be used for reclocking your PCI card, a Sonos or even a CD transport. Reviews and customer feedbacks:

http://www.empiricalaudio.com/news-and-reviews/synchro-mesh

Steve N.
Empirical Audio

Are you looking to upgrade PC parts?

I upgraded from 4GB to 8GB, laptop to custom build desktop.

From dual core to 8 core CPU.

The difference was beyond belief! 1000% times better as playing HD Audio can eat at CPU usage etc.

Better PC parts better performance!

The solution I'm going to try is a better card that has only digital outputs and claims to support asynch for improved clocking and a claimed low jitter output.

Just out of curiousity, what card are you going to get?

Short story is, everything matters with PC audio. The cable quality, electrical noise within the PC, PC power supply pollution, yada yada.

MP3s will never sound good, upsampling does nothing for them, and upsampling any file type/quality is not a guaranteed improvement.

USB works well, it's what I use, but often an external signal improvement device (reclocker, etc.) makes a world of difference. 

I built a custom PC server, all custom "audiophile" parts. Expensive. Then spent another $2-3K on external signal improvement and it made a big difference. Feeding into a $4k DAC. And there's even more I could do.

So, it never stops, you are at the bottom of the ladder now and there is a lot that could be done to improve.

How can you improve PC audio? Get rid of the PC..........