Isolation Transformers

I bought an isolation transformer from a fellow selling his home audio gear about a year or so ago. It’s a 12” cube that weighs roughly 60 lbs and has 8 plugs in the back. It was apparently used in a hospital. 
I have most of my gear including a tube preamp plugged into it mostly for protection purposes. It puts out a constant 124v which is a few more than what I get directly from the wall socket.
Anyone else using this sort of device as a “power conditioner” and what are the pros and cons of using one? I’m guessing delivering a constant voltage (almost) regardless of the load is the main advantage of this type of device but am wondering if it impedes full current delivery at high amplifier loads. Thanks.