Help. System sounds thin and bright or harsh

Another update  and reversal.  Spoke with Mark at Reno HIFI where the Pass amp came from (x250.5) After telling me that the amp is likely not the culprit and describing what I SHOULD hear if something in the amp was failing. I finally hooked up the balanced outs from the Modwright/Oppo directly to the amp using the variable output for volume control. (many here had suggested that, Im just a slow study)  Much better, smoother but kind of laid back lacking a little in dynamics.

Then, per Mark, pulled out the stock power chord to the amp and disconnected amp from the power conditioner via after market chord and used stock chord from wall straight into amp. Better still, Parasound JC2 is now out of the mix...power conditioner still handles modified disc player.  Gonna pursue future upgrades from this particular set up.  Front end first, I think.  Still wondering if a better preamp might bring more to the party???  

"A pair of subs"

they won't make the sound warmer. It's going to be surgical to sync them up with the Harbeths

Unfortunately a better preamp will help, larger speakers, and swapping the amp. It just sounds each will make a pretty big difference, but one itself is unlikely to make the full jump you want. 
 

If you come to that conclusion as well. Typically it is best to start by choosing speakers first. They are the most important component of a compatible system (with well chosen equal level components). As true as this is, I always have valued my preamp most and would get this right (and the very best I could afford) and then  carry it over more than one system upgrade. 
 

I think I need to try a different pre amp the ooomph has gone away. Not as bright and brittle but less weight.  

My preamp has been the thing I loved the most… still is, my Audio Research Reference 6SE… the heart of my system. 👍