You may know that we subscribe to the Classical Music Library streaming audio tool. Now when you search our online catalog, if a recording is available in CML, it will have it's own entry.
Here's a Boolean search for Reger and serenades, limited to "music recordings."
If you click on the title, you get more information about the recording.
You can then click on the link that says "Online Access" to go to the CML tool, where you can click on tracks to play them.