What front end piece should I upgrade?

You experience with that DAC is not that unusual.  Wonderful unit but soft bass is a critique I have heard from more than one customer.  I would look at new or used Bricasti M3.  It is a very common upgrade for folks moving from PS Audio DACs.  You could also look at the Rockna Wavellight or Canor DAC 2.10.  These are all going to be neutral to a hair warm and will have great bass response. 

The other brands that may do well for you is Aqua.  I don't know the models all that well but I know they will have a sound profile that should meet your needs. 

Full disclosure, I am a dealer for Bricasti & Rockna, I am the importer for CANOR and have no relationship with Aqua

Get the Sonore OpticalRendu to replace the ultrRendu. Fibre Optic cable is something I can easily hear the benefits. Fibre is made of glass and glass cannot carry analog noise from your network into the DAC. Your ultraRendu likely does a good job, the opticalRendu would be better.

I have 2 systems with 2 network switches that provide the gateway to a fibre optical signal. One cost $79 and the other was $150, though the $150 was around $500 on Amazon recently. 

BTW - I have the Sonore 'audiophile' power supply and other audiophile stuff for my 2 streamers. If I were to do this again, I would save my money and use the regular power supply and cheaper whatever. As long as you have fibre just before your DAC then I do not think you will hear the difference with gear before the fibre.

@seaside 

Your system looks great, but if I was to nitpick a little, I’d replace those Monster IC’s with some a bit more up to date, like something in the midrange of the Audioquest line. ( look for used!)

If you are looking for more bass, look at a SVS PB 1000 Pro or 2?

All the best.

Keep playing with the Roon dsp. Try a parametric eq boost or cut centered at 5khz and from from 4-6khz to change “pierce” effect in the sound to your preference. I like a 2-3 db boost there on my systems with both Sonus Faber Concerto Domus and Ohm Walsh. If your room is acoustically challenged like mine a lot of DSP room correction may be needed for best results regardless of what gear you use. Also a steep high pass filter set at 20-30 hz or so would place less demand on the amp and improve performance. You have good stuff assuming all is in good operating order. If not then get repaired or replace. Tweeters and crossover in good shape? Roon DSP should be able to take things to a much better place if needed including applying a custom room correction filter. You can create one of those for your room using REW freeware on a laptop using a decent quality microphone. Good luck!

Thank you everyone for the input.  First, I will make the suggested changes to the Roon parametric equalizer.  Second and after reading reviews on the Kimble 4TC, I appreciate the recommendation to upgrade them.  Most reviews indicate they are best for satellites with a subwoofer (I used to have KEF satellites with a subwoofer but they did not work in the larger room in our new home) as the Kimbers were found to have weak bass and the high end was somewhat bright and harsh.  Those AZ Satori Shotgun (used) sound great.

Third and moving onto the recommendation to upgrade the Monster XLR interconnects, I should have said that they are M1500s with a retail price in 2005 of $400, although I purchased them used for $125 when I got the PS jr.  Thus, I never listened to the DAC with any other interconnects.  According to reviews(3 combined into one), "The M1500s are in a different league from their much cheaper brethren. Their build quality is substantially superior (they have very sturdy yet flexible outer jackets) to the M850i, M950i, and M1000i cables.  In fact, one of its strengths is the connector. It uses a solder less design that was employed on the Sigma. They were also much more expensive new.  I would say that they are a fairly good and neutral cable, and that they compare rather favorably with the Audioquest Emerald's that now reside in my system."  

So with that new info, do folks continue to believe that I should upgrade them?

After I complete those steps, I will weigh whether it is better to upgrade the DAC or move from the ultraRendu to the opticalRendu.  These would clearly be more costly upgrades and if the changes to the speaker cables and interconnects would resolve the harshness and begin to address the weak bass response, I may be able to live with my ultraRendu and DAC with some tweaking of the Roon parametric equalizer.

Please let me know what you think and again, thank you all for your suggestions and expertise!