Can the tube experts and aficionados comment? Might be relevant...
From a thread resurrected by @mozartfan circa 2003 and posted by @clueless
"My limited experience so far is that drivers actually contribute a stronger sonic signature than the output tubes, which are pretty transparent if driven by a low enough source impedance and low distortion. Arthur Loesch tracked me down at the CES a few years ago, and as we chatted and toured the rooms at the Alexis Park, he mentioned that most DHT's sound alike - if driven by a low enough source impedance and a powerful driver with *lots* of current. It's when they are driven by feeble 5-8mA driver tubes that the characteristic 45, 2A3, 300B, or 845 signature appears. In other words, you'll get loads of that 300B sound if all you're using is an RC-coupled 6SN7."
- end quote Lynn Olson