Need help. Music server and streaming. Newbie.

Your Oppo can be used as a streamer using the Network Tab.  I would start there, since you already own it.  It isn’t the most elegant streamer, but it gets the job done.  What it doesn’t do is Internet Radio or Tidal/Qobuz, the two streaming services that do CD quality or better.  The 205 has a very good DAC so you don’t need to buy a new one
  You need a HD to connect to the Oppo.  Something like a 1TB Western Electric Drive can be directly connected via the Oppo usb input so you don’t have to worry about WiFi vs Ethernet.  Alternatively you could connect a laptop and use the HD of the laptop and use the laptop for streaming sources and internet radio.
You will need to convert your CDs to whatever HD you choose, and that is a whole different topic

I have Oppo 205 and Sony HAP-Z1ES.  The 205 is a lot better, especially when using XLR analog output.  I agree with @mahler123 suggestion you can start with connecting USB drive to Oppo 205 USB port, but please note that you will get better sound quality playing CD/SACD directly on 205.  Playing from USB drive gives the convenience of selecting folders/tracks from Oppo app on phone/tablet.

Thanks for the input so far......

I forgot, I have a 1TB Toshiba back-up drive for my desktop......I will try that tonight in the USB port. 

Won’t sound as good as CD/SACD?

Hmmmm........Preferring to not lose quality. Let’s see....

Try ripping a couple of CDs to the hard drive as FLAC files, share it on your network, then stream through the Oppo and see how you like it.  Or connect it directly vis the USB port.

iTunes doesn’t do FLAC files, does it? Or what software do you use?

Foreraus, I went your route years ago until I bought a dedicated streamer dac in one box and eliminated the computer interface. I also got better sound. You are correct ITunes saves as AIFF not Flac....or whatever Apple calls it. I put my multi thousand CD library onto a solid state outboard hard drive and just plugged it into the back of my Lumin, which streams just about anything. If you want a simple, uncluttered solution I suggest picking up a one box unit to plug into your hi fi. Streaming is the "new" direction and I believe it’s here to stay.

For certain I am no expert in this area , but I import cds into itunes using WAV setting and error correction and find the result to be very good. I have seen online that if you have a large storage capacity that Apple Lossless Encoder is the best option

Not meaning to hijack but @tuberist what model Lumin do you recommend or have?  Been dealing w/an ailing aged CD player laser drive and about to jump ship.

I don't use iTunes, or any Apple products, other than an old iPod that I never use anymore, thanks to my phone.

I use Foobar 2000 for ripping CD's.  There are other formats you can use as mentioned.  The key thing is to use a format that doesn't employ compression and works with what you're using for playback.  I know FLAC works with the Oppo.  The others may also, but you should check.

Foeraus, I decided to use existing computer, next to my listening chair. I use WiFi in order to avoid dragging cable across the room.
Quality of digital music when delivered data is perfect (aka "bit-perfect) lies in timing of D/A conversion. When this conversion is done in uneven intervals (jitter) additional frequencies at small level are added resulting in added noise. Conversion timing can be dependent on incoming signal (S/Pdif, synchronous USB) or independent of it (WiFi, Ethernet, Asynchronous USB). Even in case of independent clock there is still electrical noise (converted to timing jitter) injected by the cable. In case of WiFi, everything depends on quality of the receiver (timing evenness). I use Airport Express, that is not available anymore. You can still get Apple TV, but the problem is that it operates at 48kHz - frequency common for TV audio. CD data made at 44.1kHz has to be approximated for the new timing. I’ve read post about loss of quality while other people claimed it is inaudible. WiFi receiver produces some small jitter on the output. To reduce it you could use jitter suppressing DAC (I use Benchmark DAC3) or suppress jitter with added reclocker.
USB seams to be a good solution as long as it is asynchronous. In such case you transfer just data while D/A conversion runs at independent timing. You have to be careful to avoid injecting electrical noise. You should select cable without power wires, if your DAC doesn’t need it. Good shielding might be important as well.

Now, ripping CDs. Itunes with necessary error correction enabled works fine when CDs are in good shape, but for poor ones it starts interpolation of missing data. CDs were designed with error correction and interpolation assuming that CDP cannot (working in real time) read the same sector many times. Itunes most likely reads each sector few times but dedicated ripping programs can do this much better. You can set number of times you allow to read the same sector or even verify that operation was bit-perfect (CD checksum). I use free XLD for Mac, but Windows people often use Exact Audio Copy (EAC).

Formats: You should select lossless format. It can be either uncompressed or compressed. Compressed will save about 50% of disk space. WAF and AiFF are uncompressed while FLAC and ALAC are compressed. WAF and FLAC are more common in Windows while AIFF and ALAC are Mac formats. I use ALAC.

I like WiFi because it makes sound quality independent of anything on computer side. Computer speed, type of HD, amount of memory, playback programs make no difference. I use computer for other tasks during playback and it doesn’t affect the sound either.

Backup: Rip CDs that you want to listen at given moment. My XLD places them in Itunes directory and I can start playing CD during ripping just after first track of CD is done (ripping is faster than playback). That way it will not be a big chore. Make backup. I use 2 backups interleaving them every 5-10 CDs. On of them I keep outside of my house just in case of theft, fire etc. Total of 3 HD gives me extra protection in case of computer failure (or virus) during backup, that can destroy two of them.

Leave your desktop computer and your HD’s where they are. Rip your CD’s to your desired format. Setup UPnP/DLNA on the computer. Get a Simaudio Moon Mind 2 Network Player ($1900). It will stream from your computer and works with Tidal/Roon. etc........Plug the Mind2 into your OPPO (since you like its DAC) and presto. I use the Mind 2 plugged directly into my pre/pro over AES and it sounds fantastic. I stream Tidal from it, as well as all the content from my MacPro.

I use a Bluesound Node 2 for streaming in my lounge. I ripped all my DVD-A and SACD's using "DVD Audio extractor" for DVD-A and my Oppo 103 for SACD's (ripped with "iso2DSD" over a network connection), "Exact Audio Copy" for CD's.

The bluesound node 2 is also hooked up to Tidal.

For storage and as a server I use a QNAP NAS running a Roon core and the Node 2 acts as the end point. I control this with the Roon and Bluesound ipad app which works really well. The nice thing about the NAS is not running a PC all the time as well as RAID backup. If you get one with enough grunt running Plex is awesome for managing and streaming video. Another added plus is if you buy a plex pass you can watch and listen to all your video and music (not DSD) anywhere in the world through your iphone, ipad or Roku plugged into a hotel TV.

When I want to stream multi channel recordings I do it via DNLA through the Oppo 203. The Oppo has a less than stellar interface for playing music meaning the browsing can be tedious. The Roon interface on iphone and ipad is really nice to use. Apparently you can get the Bluesound Node 2 to throughput multichannel FLAC and DSD but only when it isn't used as the DAC but I haven't tested that.

For my listening room I have a PS Audio Direct Stream DAC with network bridge for streaming and DAC for disk playing, but that is at a higher price point.