There are a number of factors that could contribute to excessive noise coming from an SRM450. Of these, one of the most common of these is the use of unbalanced lines are naturally more prone to RF and other induced noise, thus it is always better to use a balanced connection whenever possible. When troubleshooting a noisy system, the first thing that should be done is to isolate the signal source, and establish that the signal there is clear of noise. Once this has been established, equipment can be connected back into the signal chain and monitored until the source of the noise can be established.