Is an isolation transformer better than a power conditioner?

I am an engineer, importer, and manufacturer. Among the products I have manufactured is power generators and UPS systems. I would suggest the cleaner the power going into equipment the less ripple seen at the power supplies. There is a weak link in your system somewhere. A good dealer should be able to find it and help you correct it. Personally I am not a Shunyata fan and would suggest removing them from your system.

It improves the SQ but not dramatically. And it is two large chassis that take up a lot of real estate. And not particularly attractive. And we’re $18K new! One would expect transformative performance."

You spent $18K, and yet...

Testimony for the curious-yes, it all MADNESS!

I am a very firm proponent for balanced AC electrical power for audio components.

Me too!

That’s one of the reasons why I run all my audio gear on 250 volts, its balanced voltage not needing a neutral or balanced load. Also, the sound quality is better, and it negates the need for a balanced AC PC/isolation transformer. That’s been my experience with North American voltage (USA). FWIW: Because the amp is now running at twice the voltage but half the amps (current) the wall wiring looks twice as thick to the amp as it does at 120 volt (ohms law). Now the amp makes even less audio noise on the line and it then rejects its own line noise better. The 220 volt outlet can be a standard 15 or 20 amp with 12 Ga wire.

Mike

I found that the hum from my larger isolation transformer, in the same room as the equipment, was too loud to tolerate.   They all hum and imho a large one must be located outside near the box.  I agree the improvement is slight.

For years I had hum, incoming voltage running between 123-126v in those years. Since repairs, 119-120v 24/7, no perceptible hum ever. Over voltages and dc offset  usual causes of transformer hum. Mounting them properly very important as well.