Media Vision Technology Inc has been given the thumbs-down by Standard & Poor’s Corp, which cut the rating on the sound board maker’s convertible subordinated debentures to D for Dead from triple-C-minus – intensive care with little likelihood of recovery without drastic surgery. About $115m of debt is affected. The action reflects the filing for protection under Chapter 11 of the US Bankruptcy Code – it expects to report a net loss of $80m to $90m for 1993, $60m to $75m for the first quarter; its liablities exceed assets by $100m.