Be careful that you are not chasing your tail.
The European spec for mains voltage is
here, It says that: The nominal European voltage is now 230V 50 Hz (formerly 240V in UK, 220V in the rest of Europe) but this does not mean there has been a real change in the supply. Instead, the new "harmonised voltage limits" in Europe are now: 230V -10% +6% (i.e.
207.0 V - 243.8 V)
All modern electronics sold in Europe has been designed to run happily and normally from at least a minimum of 207V to a max. of 243.8V. As you cannot be sure what your incoming voltage is, you may find that your double-transformer method is actually giving you well below 207V i.e your incoming is not 240V as you think but could be as low as 207V yet be in-specification.