Should I PURCHASE AN EXTERNAL DAC

Until you upgrade your sources to lower the jitter, the differences will be small.  I continue to hear audiophiles say that a $200 DAC sounds the same as a $2000 DAC, or that all DACs sound the same.  This is why I highly recommend upgrading your source or reducing the jitter from it.

Here is typical jitter from a transport:

http://www.audiocircle.com/index.php?topic=154408.0

If you intend to use a transport, then you have 2 choices: buy a very expensive transport to lower the jitter ($5K+), or use your current transport and lower it's jitter with a reclocker like the Synchro-Mesh ($599).

Once you have a low jitter source, only then can you properly audition DACs and S/PDIF coax cables.  Then you will hear the real differences and be able to make an informed choice.

Unfortunately, you will not be able to do SACD with an external DAC.  You will still need the analog outputs from your CDP.  Nothing much can be done about SACD jitter, except to mod your DAC, which will reduce jitter, but not nearly to the level of a good reclocker.  If you don't have a large SACD collection, don't bother.  Your CD collection will probably sound better than the SACDs anyway.  Treating CDs with coatings and other tweaks to reduce CD jitter are not necessary if you use a Synchro-Mesh reclocker.

Steve N.

Empirical Audio

It seems like what I read on this forum the vast majority are not into home theater set ups , just 2 or multi channel music. I love my music but I enjoy a bang up movie too working that sub!

l am in the 2-channel biz, but I prefer HT myself.  I also have a dual system.

I have a tweak for you that will lift your HT system to new heights:

Jitter from the OPPO is again the issue, as well as jitter from your smart TV or cable box if you use one.

The fix is like my Synchro-Mesh reclocker, but this IFI SPDIF iPurifier reduces jitter for Dolby Digital and DTS:

https://ifi-audio.com/portfolio-view/accessory-spdif-ipurifier/

At $149, it's a no-brainer.  Just buy it.  It has coax and optical in and out, so compatible with any system.

The Synchro-Mesh is the one to beat for 2-channel, but the iPurifier is the best thing for HT.

If you have a flat screen between your front left and right speakers, you would greatly benefit from diffusors between the back of the speakers and the screen.  In my system, I use 1/4 round tube-traps to scatter the backwave from the speakers.  This improves depth and width of imaging and improves focus.  Putting a quilt over the screen does not cut it.  Check out tube-traps from ASC:

https://www.acousticsciences.com/products/fractional-tube-traps

You can find 1/4 rounds used on ebay sometimes.  See how they are used in my older setup:

http://www.empiricalaudio.com/about-empirical-audio/

Steve N.

Empirical Audio