LAST year's High-End Audio show was described as the ''very best in the world'' by visiting foreign manufacturers, according to Ming Fat marketing director Miu Pui-tim. This year's show starts tomorrow at the Regal Kowloon Hotel. The $110 per day entry fee will entitle visitors to a complimentary compact disc and a chance to enter the grand prize draw. The grand prize is a $300,000 audio/video system. There will be many other secondary prizes. About 50 exhibitors are participating, representing a range of high-end products. Many have set up their own sound rooms for visitors. During the last show, thousands of audiophiles sampled some of the most esoteric audio and visual components available. They also saw some of the world's top audio design innovations. This year's show promises to be even more successful. ''The organising committee of the High-End Audio Society of Hong Kong is aware of the show's expanding potential,'' Mr Miu said.