Well I am not sure if this is true. I got an AVR from US with the regular 110v 60hz supply, and I bought a transformer (Jatin's advice) from Delhi. Its by a brand called Guru, they are apparently known and branded and famous as they make the transformers themselves.
Its a 1000Watts (or 1KVA) with a single Socket at the rear. All in all the transformer is very heavy and I haven't seen any excessive heating up of the AVR.
Also, Mine is tha Automatic type transformer. It has a fuse to prevent excessive current flow. Now sure how helpful it would be.....
And I doubt there are transformers in the market which will change the frequency cycle also to 50Hz ?