The sale means that ISIS, which backed Martin Audio’s buy-out from TC Group A/S in 2003, has multiplied its investment 3.5 times, producing an IRR of 45 per cent.

Martin Audio’s managing director David Bissett-Powell says: ‘Our partnership with ISIS has been a great success and has assisted the Martin Audio team in exceeding the objectives that we set ourselves at the time of the buy-out. However, we recognise that we need to have access to a wider base of technologies and for this reason have been looking at potential partners for some time.’

London-based Martin Audio manufactures loudspeaker systems for the professional audio market. Founded in 1971, the company has supplied acts from Pink Floyd and Supertramp to Kylie Minogue and The Ministry of Sound.

Martin Audio employs about 60 people and has clients in Europe, the Far East, the US and Australia. It generated turnover of £14 million turnover and pre-tax profits of some £2.4 million for Year-End June 2006.

Pitmans and Livingstone Guarantee advised Martin Audio, while Olswang acted for ISIS.