That happened to me today. Signature Limited -> 2 Channel "H" -> Marshall 1960BV 4x12 cabinet.
It didn't sound as good yesterday, and it probably won't sound as good tomorrow. But today...it was perfect. As a result, a planned one hour session turned into the better part of three hours.
It wasn't even very loud. In fact, it wasn't particularly "loud" at all. But for whatever reason, it wandered into tonal nirvana today.
Unfortunately, it was in my basement and nobody else heard it. But damn, I enjoyed it.
Anyone ever have one of those days when it just "worked"?