Dan had the closest sound ever on one of our shows back in 2012. He used a Vox Tbx with Roger's Vintage Unit, an Atlantis echo and a Strat equipped with a set of Tonerider Vintage pickups. On the same show I was using the Australian built Vox AC30 clone, an ESE Echomatic and a Strat with Sliders pickups. The sound was identical to Dan's and we put it down to the Vox amplifiers. I have the show on video and it's unmistakably there every time we hear it.
We took the Toneriders' off that guitar and they were replaced with Kinmans' just before Dan appeared with Bruce at Shadowmania in 2012 and there was a noticeable difference in the sound, but non the less pleasing. He also used his Pinnacle amp on that gig.
When the Etap2hw became available later that year, Dan and I spent hours comparing it with the Atlantis, only to discover the Etap did everything the Atlantis could, so I sold the Atlantis on.
The sound is about the player and how he sets up his kit. Most of the bad sounds are down to 'pilot error' .
Regarding the mix up with the valves with the Little Walter amp, at the time Dan bought it we were discussing and his Matchless 15 watt amp came into the conversation, which is the one based on The Vox - My mistake, sorry.

To add to that, I was with him last night with The Foot Tappers and he used the Little Walter with a single cabinet and his Magicstomp with the Burns. I thought it sounded better in the flesh.