Computer, software, USB cable or ?

If you were running the laptop on AC a worthwhile experiment might be to try running it on its battery.  I'm envisioning not only that the AC power supply might be introducing noise into the system, but when on battery power the computer might operate in a somewhat different manner internally, in the interests of conserving power, conceivably resulting in less digital noise and/or jitter on its USB output.  And if the USB interface of the DAC in your C50 is not asynchronous, it might be particularly susceptible to that kind of issue.

Best regards,
-- Al
 

could be lack of galvanic isolation

some say SSDs sound better than a HDD - which did you use?

I suggest you post on https://www.computeraudiophile.com

where a lot of engineers involved in designing DACs and related products hang out

i’ve used lots of different approaches when streaming via computer, but here’s the best combination of solutions I’ve found to date

If the DAC utilizes the USB power (many do)
- I found the best cable solution to be a dual lead USB cable - this has separate cables for power and signal.
- get a separate power supply - Enercell does a really affordable 5v USB power supply that performs well
- Pangea and Doukmall(Ebat) sells reasonably priced cables ($50-60)

Get Audirvana streaming software - it bypasses the Apple routines which "colour" the sound.

Copy CD’s using DBpoweramp - it does a great job and let’s you know if data errors are present

Next I would consider getting a V-link192 USB/SPDIF converter - it has a superb USB interface and improved quality a lot. They are no longer made, so you’ll have to look at used

I’ve since done away with the computer/DAC/V-Link and opted to go with the Blusound Node 2 connected via Ethernet cable to a router and NAS drive.
- it’s simple(even my wife can use it), great sounding and by comparison to the computer/DAC/V-link/cables/powersupply combo - it’s affordable

The Node 2 is the best streaming solution I’ve experienced to date, but there are many similar products out there - so find one that fits you

Hope this helps - Steve

I appreciate the input, everyone.  Specific answers:

@almarg - I run my laptop on battery when connected to the stereo.  If I run out of juice, I take that as nature's way of telling me to switch to vinyl or go to bed;-).

@auxinput - The DAC in my C50 is supposedly a stereo-only version of the 5 DACs used for the 7.1 capability in the 881.  Unfortunately, the 881 doesn't allow a DAC-only loop, so can't try an A-B between the two.  I'll consider the reclocker idea, and I appreciate your brining it up.

@randy-11 - My Mac has a 500 GB HDD; the SSD wasn't available in the 13 inch version at the time.

@williewonka - The C50 DAC is internally driven, so not an issue.  I'll check into Audirvana; I've been using iTunes simply because it came with the computer.  On the BlueSound Node, a buddy of mine has one hooked up through a Hegel H300 integrated and a pair of Martin Logan ESL EFX.  The combo sounds really good, and it's something I've considered.  The issue I have there is that there is no way for me to connect a Node or Vault to my router via Ethernet.  The C50 doesn't have a wireless capability and there is no way for me to run computer cable to it of any kind short of tearing out the ceiling in my basement (long story about bad decisions by prior homeowners).  The USB connection I've been using is a Rube Goldberg rig that I uncoil from the bottom of my audio rack and run across the floor to my laptop when I want to use it.  Makes it a real PITA for streaming Internet radio.

FWIW, I did just discover that the C50 automatically up-samples all digital inputs from whatever to 32/192 internally.  Amazing what happens when you re-read a manual after a few years.  This defeats (duplicates) the MIDI configuration in the laptop and raises questions about hi-rez file handling.

More to follow & thanks again!