is it possible to fit a power shower on top of the tiles without spoiling them?

Yes if you have a loft above your bathroom, it is possible to run your water feed pipework in chrome to make it look better then it would in copper ,if your in a flat maybe a bit more challenging but still possible its just a case of picking up the water feed pipes from somewhere good luck and I hope this helps

Hello. As mentioned you can run chrome covered copper pipe. You can tee off your cold feed for the bath . If you look at my profile you can see what a shower looks like with face mounted pipe work . ( the tenant wanted it in plains copper pipe though) Not knowing your layout , dropping pipe work and electrics down from the loft in the stud wall would make a very neat job . The feed holes for the shower would be hidden by the shower. The pipe work is very simple, obviously you will need an electrician to wire you shower in. Or you maybe lucky and have an airing cupboard next to your bathroom . Hope this helps