Mr Amoroso claims that DRM enables tiered use of digital content.

"For example, DRM is uniquely suitable for metering usage rights, so that consumers who don't want to own content, such as a movie, can "rent" it. Similarly, consumers who want to consume content on only a single device can pay less than those who want to use it across all of their entertainment areas – vacation homes, cars, different devices and remotely," he says in his letter to Jobs.

The argument for the use of DRM in rentals is a furfy - it has nothing to do with FairPlay or PlaysForSure which are designed purely for purchased content. As for charging consumers different rates according to what devices they want to play their music on - well perhaps Mr Amoroso should do some market research to see what consumers think of that idea.

Way back in the 1970s, we had the notoriously fragile vinyl records and pre-recorded cassette tapes for sale in music stores. It was a common practice for consumers to buy a record and copy it to a blank cassette. The cassette was lesser quality but was it was smaller, easier to handle, more convenient and portable because it could be played both in the home and played in the car.

To be honest, I'm still not sure whether making a cassette copy of your own vinyl record for personal use was legal. However, I am sure that the common practice of making cassette copies for friends was totally illegal. Despite this and the fact that often poor quality pirated cassettes were being sold openly across Asia and even in local flea markets, the legal recording market thrived. Most people were prepared to pay the price for the genuine article because they wanted the assured quality.