If your preamp has only analog inputs, then you will need a Blu Ray that has analog outputs. Analog outputs are a weak spot for Blu Rays the feature them (many do not) as they tend not to put a lot of quality into analog outputs.
You could also get a DAC that will accept the digital out from the Blu Ray and then connect to your preamp with via the DAC analogue outs.
You could also get a DAC that will accept the digital out from the Blu Ray and then connect to your preamp with via the DAC analogue outs.