I know a guy who bought a load 110V studio gear from a guy selling up here ,
So he ended up with a mix of 110 and 230 v gear running in the studio ,
There wasnt a good system in place to differentiate the 110 and 230 v circuits , like colour coded plugs /cables ,
clear labeling to tell him which pieces were 110v and some form of non mating recepticals to help prevent the wrong voltage being applied .
He ended up blowing the crap out of loads of stuff by connecting it to the wrong supply .
So lets say you have your 110v supply , neutral bonded to ground at the utillity in the usual way , then you have a 240 step up with a centre tapped ground , what happens if someone makes an audio connection between a 110v and a 230v powered device , or even makes physical contact to metal work at different potentials ?
So obviously the safety of the people using the gear is the primary concern ,
Theres inherent differences between the US 110v and the 230v EU system ,
I hesitate to give any advice in this respect , I'm not well versed enough .
Safety of the equipment is secondary , but again its difficult to make it fool proof when you want guests to be able plug and play , the safety requirement might fight whats best practice in terms of noise , what happens if someone arrives with a miswired bit of equipment plugs it in and the thing becomes unsafe in some way ?
The guy I knew who blew up much of his gear by applying 230v to 110v equipment could have saved so much trouble by simply
reconfiguring the 110v stuff to 230v on the back panel in many cases .
The safety convention here in Ireland is 110v is yellow , 230v blue and three phase is red , each system has its own unique keyed colour coded receptical and connector that wont mate with the others , and in the case of 110 and 230 they also use yellow and blue cable respectively .
We had a few non export model US made tube amps down in Sulan , each had its own 230-110v transformer installed , probably around 250-500VA , We kept a few smaller iso and autoformers for the clients to step down if they required it we'd figure out the best way to do it on a per case basis , more often that not they brought their own arangement to get 110v .
We didnt make 110v available to the client from the wall anywere in the building appart from the shaver sockets, If you do want to make your own 230v supply for the owners gear my advice is make it in such a way theres no possible way anyone can hook up without oversight of staff and a special adapter cable .
Nothings fool proof 100% , there are intrinsically safer ways to do things though .
Best of luck ,