Why use CD Transport instead of computer source

I'm considering adding a SB3 or Sonos to my Bryston BP-25DA, which allows for two digital sources. I've been researching for a couple months on this topic and found several reasons why CD transports may sound different from streaming sources:

- Power supplies: Better power quality = better sound. The stock SB3 may have an inferior power supply to a high end transport. Even modified linear SB3 power supplies may not fully match the careful planning and routing of power in a top transport.

- Impedance matching: Poor matching = reduced performance. It's possible that the transports have an isolation transformer to better match to the recommended 75 ohm impedence. Impedance mismatches can cause jitter.

- WiFi - WiFi is great as a wireless convenience solution, but it is certainly not an optimum signal transfer mechanism. Almost always better to use a hard-wired Ethernet connection for streaming files.

- The computer. If the data source is not a dedicated music server, it's possible to get an audio performance hit if the CPU is nearing the multi-tasking limits. Network attached servers seem to be the best current solution.

What I have not seen as a plausible source of difference is the use of a hard drive vs. an optical drive. Optical sources are inherently less reliable than hard drives, that's why CD encoding contains so much inherent error correction. But, a hard-drive with an overworked CPU could be a problem.

A friend and I compared/blind tested a 12k CD player vs. a Mac/USB DAC combination and in most cases, we were unable to determine which was which. This was a blind test which was conducted within a cost no object system.

Like someone said above, the cost of a beloved transport perhaps can affect someone’s opinion.

The test was done in a dedicated listening room that has been well treated for room acoustics. The system is a system we are both very familiar with, the listen levels where matched, and we choose the same listening material, started at the exact same time.

We switched back and forth between the two inputs via the Sim Audio preamp. The preamps display was blocked so that the person taking the test could not see which input was in use.

The end result was that we could not tell which source was playing even though we could recognize slight details between the two. Neither was better, neither was worse than the other. The deciding factor was the user interface of the Mac setup was better, plus the ability to access the entire music collection without leaving the listening position sealed the deal.

Like I said up above, cost is no issue. He can have any source player in the world and he has chosen a hard drive based source.

Jstovall389 - WiFi will not suffer sound quality hits over USB. In fact USB is more difficult to get right. WiFi is always bit-perfect. Only jitter has to be dealt with. The only disadvantage of WiFi is some times it gets interference from wireless phones or microwaves, and it is limited to 16/44.1 in most cases.

As for computers at their perfomance limits: This usually only happens with USB and it is a latency issue. Even the CPU at 10% utilization can cause pops and ticks if the system is poorly set-up. If the optimum drivers etc. are used, USB can be problem-free and has the advantage of supporting 24/96. The sound quality is never affected by this. It only causes momentary drop-outs when it happens. The bigger contributors to SQ with USB is the clock used in the converter, the USB cable, the chip doing the ISB to I2S conversion, and of course the circuit-board implementation.

Steve N.
Empirical Audio
Manufacturer