Importance of clocking

A recording studio is using an external clock as much for synchronization as for anything else, as they often have a situation when devices are daisy-chained together and must work together correctly at every clock beat.  The multiple pieces of equipment can't "hear" each other the way an orchestra does, so the master clock is there to make sure all the different pieces are in synch.

It's the daisy chaining effect that CAUSES jitter unless mitigated by the master clock.

On the other hand, with Internet streaming, there's no such synchronization. 

PS- Error correction is taken care of by the TCP portion of TCP/IP and handles requests for retransmission when packets are corrupted.  Another reason for big buffers, having enough time to ask for a retransmission when an error occurs.

It is helpful to clarify whether the application is using s/pdif or asynchronous USB.

For s/pdif, I think DCS uses what they call "reverse clocking" to minimize jitter in this case an external clock makes sense.  The clock comes from the DAC domain and is used to clock out the transport data.  In this case it is mostly mimic what you  have to the asynchronous USB.

For asynchronous USB the data clocking comes from the DAC domain so an external clock may not help much.  For this, you probably want to have the clock physically as close to the DAC as possible which is the implementation of most USB DAC anyway.

But there is a but.  In asynchronous USB, if the incoming data has a lot of noise, it may inject that noise into the DAC circuit, so you could argue buffering the data with a reclocker will clean up the noise and therefore improving the sound quality.

Andy has a very good point. In the case of SPDIF or AES the clock is embedded in the data stream is more prone to jitter therefore the clock of the source/streamer is critical and IMO could benefit from a good reclocker with a good clock cct and its associated PSU. There are some transports that have a clock input so that the clock from the DAC can be used to clock the data in the transport. As Andy says async USB is supposed to eliminate this issue since the data is clocked by the DAC. Again I agree that a good reclocker/DDC could clean up the USB jitter (noise) but it all depends on the quality of the equipment. The reclocker’s clock needs to be of superior quality to that of the DAC’s one. I believe I2S is the best interface available, it was first designed as an interchip protocol but I see lately is being used to connect sources to DACs. That is fine as long as the interconnects are kept as short as possible.

I had a highly modified Oppo used only as a digital transport (all audio/dac board removed e.t.c). One of the mods was an upgraded clock - but not just that - a unique dedicated linear power supply just for the clock alone. This hugely lifted the performance of the transport. I was running it spdif out to an external DAC.

Interestingly the clock was a SAW (Surface Acoustic Wave) clock, not an TCXO or OCXO. The people behind this mod were adamant that SAW clocks were superior in sound quality to OCXO clocks. I have never seen anyone else in the high end audio industry even say they have tried SAW clocks.

Unfortunately the Oppo mainboard itself died and all those mods (like a full on R-core LPS powering the mainboard) turned it into a paperweight. It was a way better sounding transport than any entry or medium level product you can get now.

Spend your money on a good DAC that includes a good clock.  Spending thousands on a clock is a huge waste of money, IMHO.  

As mentioned earlier, the main purpose of an external clock is to synchronize multiple devices, not to improve sound quality. 

If there is an improvement in sound quality, it's going to be much less than you could have realized by putting your money into a great DAC.  Lipstick on a pig and all that...