Firstly, forgive my lack of knowledge, I'm a total n00b with A/V stuff. Also, I tried searching threads but I couldn't really find anything with my particular problem.

I have a Samsung BDP-3600 blu-ray player and an older Onkyo receiver. The receiver doesn't have an HDMI input but it does have multiple optical audio inputs. If I want to run the sound from the blu-ray player into the receiver, what do I need?

For that you need an optical(Toslink) cable of suitable length. You will also need to run a separate video cable. That can be HDMI or component video directly to your TV.

Doesn't that player have multi-channel analog outputs? If the receiver has multi-channel analog inputs, you can use them for lossless codecs like TrueHD. Grab some analog audio cables (red/white RCA ended cables, you'll need a cable for each output) and hook it up.

Optical limits you to legacy Dolby Digital and DTS 5.1, but it will still be surround sound, just like on DVDs.

I have an optical cable that's long enough and I have an HDMI going from the blu-ray to the TV. I was looking online and I saw a 2-in-1-out HDMI switch that has two HDMI inputs, an HDMI out, and an SPDIF out. Would I need something like that, e.g. running an HDMI from blu-ray to the HDMI-in on the switch, and then an HDMI to the tv coming from the HDMI-out, and finally an optical cable coming from the SPDIF-out into the SPDIF-in on the receiver?

EDIT: so I shouldn't worry about the optical cable; I should just use analog cables to run the blu-ray to the receiver?

I have an optical cable that's long enough and I have an HDMI going from the blu-ray to the TV. I was looking online and I saw a 2-in-1-out HDMI switch that has two HDMI inputs, an HDMI out, and an SPDIF out. Would I need something like that, e.g. running an HDMI from blu-ray to the HDMI-in on the switch, and then an HDMI to the tv coming from the HDMI-out, and finally an optical cable coming from the SPDIF-out into the SPDIF-in on the receiver?

EDIT: so I shouldn't worry about the optical cable; I should just use analog cables to run the blu-ray to the receiver?

I wouldn't use analog cables. You'll need 6 of them and whatever bass management is in the player will probably not be as good as your receiver's.

I would just use an optical cable for audio. Set the player to bitstream and be happy. As Tulpa noted you will be limited to the legacy codecs: DD and DTS, but they will be of higher sound quality than on DVD. It is doubtful you will be able to tell the difference between these higher bitrate lossy tracks and the new lossless codecs. For some reading and an example check out this link. (http://www.hemagazine.com/node/Dolby_TrueHD_DTS-MA_versus_Uncompressed_PCM)

Since you already have an HDMI cable running to your TV, your video side is taken care of. Your player may have a setting that needs to be set to "optical audio output" or something like it.

There is no need to use any adapter like the one you saw online.

Thanks for your help everyone. I didn't realize I needed to go into the player settings and receiver settings and select the proper audio source. This is actually my first foray into A/V stuff and it's all really cool.

I wouldn't use analog cables. You'll need 6 of them and whatever bass management is in the player will probably not be as good as your receiver's.

I would just use an optical cable for audio.

Not a thing wrong with the above other than that is what Easyaspie would do. I would, in fact, run analog cables from my Blu-Ray player directly to the inputs on my receiver and keep the HDMI cable from the player to the TV. I realize that there is debate about whether the difference in SQ between lossy and lossless is significant, but if you can take advantage of lossless why not? In fact this is exactly what I did in my second HT room from my old Yamaha RX-V2095 and it works perfectly. :)

All it costs is 6 analog cables and most everybody has some kicking around or if you have to buy them what, you're out less than $10.

Not a thing wrong with the above other than that is what Easyaspie would do. I would, in fact, run analog cables from my Blu-Ray player directly to the inputs on my receiver and keep the HDMI cable from the player to the TV. I realize that there is debate about whether the difference in SQ between lossy and lossless is significant, but if you can take advantage of lossless why not? In fact this is exactly what I did in my second HT room from my old Yamaha RX-V2095 and it works perfectly. :)

All it costs is 6 analog cables and most everybody has some kicking around or if you have to buy them what, you're out less than $10.

All true and as long as the player has adequate bass management and distance setting provisions on board or if you happen to posess one of those rare receivers that digitizes an input of the muli-channel inputs for processing, it will work fine.