Agree about the audio control board.
My Denon PMA a110 integrated amp has 2 analog modes I usually like to use when I output XLR analog from Oppo which bypasses the entire digital circuitry and processing in the Denon, sound really good that way.
I've got it set up so I can A/b between the converter in Oppo or Denon in 2-3 clicks but for now it's all PCM via coaxial into Denon. 
Your right goi through multiple stages of processing / conversion isn't good but I can't use analog modes using coaxial still sounds good though.
		
		
	 
I have the 105 without the D but their audio parts are identical, so I know for a fact while it's analog outputs are really good, it is no better than those <=US$200 desktop dacs.
To me, you can do well by selling the 105D as it, unless you still want to use it to play discs, and just grab one of those Topping, or SMSL DACs for less than US$200.
If you really want to use balanced output then you will have to pay at least 10% more for the otherwise the same DAC by those two companies I mentioned.
Here's a couple of examples:
For $229, balanced
Amazon.com: TOPPING D50 III Desktop HiFi DAC & Preamplifier, Dual ES9039Q2M, Bluetooth 5.1, Hi-Res Audio, DSD512/PCM768kHz Support, RCA/TRS Outputs, Includes 12V Trigger and Remote Control (Black) : Electronics 
For $199, balanced
Amazon.com: TOPPING E50 Hi-Res Audio DAC – DSD512 PCM768kHz, USB/Optical/Coaxial Digital Inputs, MQA Full Decode, Ultra-Low Jitter, Balanced TRS + RCA Output, 5V Powered (E50-Black) : Electronics
For $199, balanced, use flagship latest ESS DAC IC, but still the Q2M version, with trigger and 10 band PEQ
Amazon.com: TOPPING DX5 II Hi-Res DAC & Headphone Amp Combo – Dual ES9039Q2M, X-Hybrid Amp, 10-Band PEQ, LDAC Bluetooth 5.1, 4.4mm Balanced & 6.35mm Headphone Output, Preamp Mode, 12V Trigger (Silver) : Electronics
For $349, this one use the best AKM DAC IC:
Amazon.com: TOPPING E70 Velvet - High-Performance DAC with AK4499EX, Bluetooth 5.1 LDAC, Ultra-Low THD+N, Selectable Output Levels, USB Support DSD512 & PCM768kHz, Coaxial/Optical Inputs (Silver) : Electronics
For $599, one with one of the best ESS DAC IC one can get:
Amazon.com: Topping D70 PRO Sabre DAC ES9039SPRO XU316 Bluetooth 5.1 LDAC Aptx-Adaptive HiFi Decoder (Silver) : Electronics
The unbalanced versions will obviously cost less.
Any of the examples I listed above will outperform the Oppo by a significant margin (on paper, based on specs and measurements), and they can play just about any digital files you can obtain at the moment, except of course, they don't play discs.     If you do play discs, then just keep the Oppo too and and do it without using analog outputs, or rip your favorite discs with you PC.     Actually, for discs, I just can see a reason for using the Oppo's analog output, I mean in terms of sound quality.
You can buy the analog board and do  your own repair but there is no guarantee that everything else will be fine, or send it to a reputable repair shop, and be prepared to pay much more than the cost of a desktop DAC.
I like balanced connection too, but they offer absolutely no sonic advantage, not even in theory, unless you have to use lengthy interconnects and/or for some reasons you wiring layout cannot avoid picking up noise.