Wow, I have just gone through a similar process in evolving my system. I ran my system for a long time with a Wadia CD player acting as my preamp directly feeding my Krell and then into my B&W 801s. I didn't know what I was doing with that approach to volume control, but now I do. It broke in 2018 after a power surge so I bought an OPPO 205 as modified by MODWRIGHT as it could act as a preamp like the Wadia. Soon after a trusted friend mentioned to me that I was missing the potential in my system without having a preamp. After doing a lot of research on that idea and preamp models, I bought a Rogue RP 7 and it made large improvements. A few months latter I changed speakers to Wilson Sasha 2s and didn't have enough power with my Naim DR300 that drove the B&Ws. I REALLY wanted to buy the DragoN from Rogue but also looked at the Bel Canto line with its great reviews. There is so much negative back and forth about class D it made my head ache, but in the end I went with traditional big ass heavy hot running SS and am delighted, amazed really that amps to do SO much. in my reading this one thing kept coming up. I kept hearing strong recommendations to go with very powerful SS (high current) amps and tube or hybrid tube preamps as a solution (if you were not going one brand preamp/amp.)
In December I convinced myself to try tube rolling the RP7 as a way to better feed the Sasha 2s. I was told that by changing the two front tubes you make a change to 80% of the sound, so I bought 2 of each NOS Brimar, Mazda, Mazda Military, and Telefunken. Changing two tubes at a time was amazing. There are trade offs, but in my system I ended up with the Mazda Military in the front and Mazda in the back. I think I could have just left the stock tubes in the back but since I had the extra NOS tubes I used them. Amazingly great sound!
To finish the story of my amp quest I ultimately bought the Parasound JC1+ monoblocks three weeks ago and then bought a used Audio Research REF 10 that I put in two nights ago. So many changes, but I am on a mission to get things right and then stop listening to my "system" and return to listening to music.
I can't comment about BC versus DragoN as I did not get to hear them, but I can tell you that SS with a tube preamp makes great music. The RP 7 has nothing to be ashamed of in my direct comparison to the REF 10. The REF 10 is a lot better, but in ways that are additive rather than showing great deficiencies in the RP7. The cost of the RP7 is very reasonable and it has been rock solid reliable for over two years. To be able to change the sound dramatically for 200 bucks is the best value I've experienced in Audio. Good luck with your quest, you have so many great choices and directions you can go!
