If your current Blu Ray player does not have a L and R analog outs (on RCAs), you could try running an HDMI connection to your TV (that will bring digital audio and video to your TV, which will decode both), and use the analog (L and R audio) outputs from your TV to feed your preamp. Not all TVs have analog outputs, but many do. The down side to this approach is that the sound (from your preamp/poweramp/speakers) and the picture will now probably not be in sync with each other.
The Oppo players all have good to excellent sounding analog stereo outputs (I have a BDP 103), so when you upgrade from your current Blu Ray player to an Oppo, this will simplify your hook up.
Hope this helps.