Input/Output line level transformers for digital glare

That can work a bit if the transformers have limited bandwidth.

But part of the problem is that digital glare is caused by a certain type of distortion called 'inharmonic distortion' which usually does not show up in the specs on a lot of digital gear. Inharmonic distortion is actually a form of Intermodulation Distortion (IMD) in that the distortion is caused by intermodulations between the scan frequency and the signal rather than intermodulations between one frequency in the signal and another in the same signal, although digital does that too.

Older systems had really deplorable performance in this regard; new ones are better and they all have it to some degree. Its hard to detect; the best way is to record a sweep tone from 20Hz to 20KHz from an analog source (if done digitally there are algorithms that bypass the resulting distortion so it appears to not be there) and play it back. The intermodulations can be heard as 'birdies'; little chirps that come and go as the frequency changes.

Normally in music the signal is changing too fast for the ear to hear these things outright, but the ear/brain system does detect the distortions and converts them to tonality, which it does with **all** distortions.

This is why you can turn the treble down all the way (if you have tone controls) and the digital will still have some glare or brightness. The brightness is not occurring due to actual treble energy, it occurs because the brain converts the distortion into tonality and there's no way to get into your brain to stop it.

Obviously the best solution is to get a digital system that does not have so much glare and these days that is really not all that hard to do. Price does not seem to be the mitigating factor either- Oppo makes some equipment that is relatively affordable in the high end audio world and yet in its stock form is not bad at all. Modright does a mod on one of the Oppo players that is outstanding. So there is something for almost every budget.

In case its not obvious, my best recommendation is to find some digital gear that is not so annoying. That will work a lot better than a transformer!

@sbank  The reason a transformer might help if it has limited bandwidth, would be to filter out digital noise. I've seen at least one DAC that sounded pretty good in its day that incorporated the inductance of the transformer as part of the smoothing circuit for the output of the actual DAC.

Of course this points to one of the major limitations of digital IMO, which is not much bandwidth on top. A typical LP record and playback chain has bandwidth to about 40KHz no worries.

I still notice all the outboard Dac's, good ones, I think
still have output transformers vs other methods

i also see the transformer guys;  lyndall & Jensen advertise the output transformers as smoothing of digitis?

Some do some don't.

A good transformer will have bandwidth well past 20KHz which means its not going to do a whole lot of smoothing. In fact if not loaded correctly it can also ring (distort) which will make it sound brighter.

Lyndahl and Jensen both make excellent transformers. If used carefully they can be of some benefit, for example they can be used to go balanced even if the output of the DAC is single-ended. You **might** get some sonic advantage from doing that as if balanced line is executed correctly, the result is that the interconnect cable will cease to have an effect on the sound of the system. If it was contributing brightness prior, then this is an advantage. They can also isolate grounds; if you have a ground loop (which can allow noise in the ground to get amplified) then the ground isolation can be help out as well.

My "test " is a Rush song called " Red Barschetta" that I found great on a lp in the treble & cymbals, but streaming or cd, nope!

It may not be the fault of the digital gear that this sounds bad. It might just be a poor transfer. If other recordings sound OK (against the LP in particular) then I would not use this as a reference.