I don't know whether stereo dave was the real thing or not, but I have no reason to assume he was a snake oil salesman.
There are outfits which modify and improve stock components. AH! Tjoeb modifies Marantz equipment and greatly improves those source components. There are many audio reviews which confirm this, reviews from sites which led many of us to Axiom products in the first place.
Check out Upscale Audio
The Upgrade Company has a good reputation. The Upgrade Compnay
There was an outfit which speciaiized in modifying Philips SACD 1000s and turned an excellent CDP into a world class player. They won't work on the Philps anymore, but they did great work. PHILIPS SACD 1000 MODS
The idea of tweaking a component of modest cost so it performs on par with much more expensive equipment should not be alien to Axiom fans ... after all, Axiom made its reputation by providing modestly priced speakers which compare favorably to much more expensive products.
There are folks out there who love audio, work at it, spend time in their work shops improving the sound from stock components.