Toslink

I think Toslink is still most likely to be an inferior interconnect. It has two extra stages in conversion that are unnecessary. Also, for most companies it is an add on just in case… so stock electrical -> optical and back. It is not so much the transmission media but unnecessary conversions.

SP/DIF has been the oldest and used for decades… then USB… needing completely different receiving processing and optical. AES is a newer, made for high end audio which I thing is just balanced SP/DIF connection.

As far as connections, in general, AES… preferred, SP/DIF , then USB (depending on DAC) then optical.

If the DAC is optical only it is likely an inferior DAC.

I think it very much depends on the DAC. If this is an older DAC, then probably. Older DACs, before USB asynchronous was ubiquitous did not have the jitter and timing stability that they do in the last 10 years or so.

If you are getting an older DAC you’ll find that upsampling really will help the performance.

Kind of for this reason I normally try to steer users away from them. The Wyred4Sound Remedy is a very good solution if your streamer doesn't already do upsampling internally.

@ghdprentice 

AES/EBU was developed before SPDIF for professional use. SPDIF is a 'consumer-oriented' variant of AES.

@yage 

OK, thanks, but in the high end audio world SP/DIF has been the preferred connection for decades and AES is relatively newer.

I have half a dozen digital pieces connected in my audio system, none using toslink connections. Only toslink connections I use is in my TV/video system. Must be a reason...