From the schematics, the lead voicing is probably more in the vein of the Mark series, but with some voicing choices that could be considered a bit Recto like, or entirely it's own thing compared to those two. To the ear--tonally--depending on how one EQs it, or even how one hears it, I'm sure some would swear up and down that it's more Recto, and others would do the same in suggesting it is more Mark style.
To me, the DC series 4x tube-stage lead channel is very Boogie. However, it varies distinctly to the degree that it's hard to feel it is convincingly "just" a Mark series variant or a Recto variant from a circuit standpoint.
Some differences of the DC Lead topology as compared to the Mk lead circuits:
- Obviously the DC only has one gain control, where the Mk type usually has two. In the DC, you could say that compared to a Mk amp, the absent gain/volume control and typical EQing between the 1st and 2nd tube gain stage are set by resistors and capacitors without any external control pot/knobs. The location of the DC's gain pot is fairly unique given that it's the only gain control in that circuit, but it IS right where the Mark series "lead drive" controls are ususally located.
- The passive EQ controls in the Mark amps are usually between the 1st and 2nd tube stage (Mark I's have it between 2nd and 3rd stage in 'lead mode'). In the DC amps, there is fixed component EQ shaping between stage 1 and 2 instead. Then there is an added internal EQ network between the 2nd stage and 3rd stage (like where it would be for a Mark I), but it is not externally controllable. It also seem to function primarily as a gain cut rather than do too much tone shaping, but I'm sure the somewhat subtle EQing it does is an important part of the sound of the DC or it wouldn't be there.
- The passive control panel EQ in the DC is after the 4th stage--at the end--"like a Marshall" and like a Rectifier there. And in the DC, a graphic EQ follows that too, so that part is a bit unique.
- The DC has much lower voltage on the preamp tubes than most amps, especially Mk amp and Recto type amps. This would typically make the gain more compressed, yield a different feel, and different "fidelity" than higher voltage circuits like the Mark series of Recto. The DC-3 has an especially low voltage preamp. The DC-5 suggest 'medium' preamp voltages like a JCM800, still lower than Mark or Rectos.
- The DC lead circuit uses small cathode capacitors in two of the Lead circuit's four tube stages. These caps shape the low frequency gain, or the apparent 'shape,' feel, and tone of the midrange to the ear. So the DC is likely going to be tighter than a Mark series amp on that account. In some ways the DC is a bit more like a Recto circuit in this particular regard, compared to the Mark amps. The Mark amps mix it up a bit, but use significantly larger value cathode bypass caps in at least 2 places for a *different* (less tight) low end feel and midrange grind/fatness/flub(?) than the Mark series amps, all else being equal--though it isn't.
- THE hallmark of a Rectifier and "those" type of lead preamps is a very drastic and distinct way of biasing the 3rd tube (usually), which causes it to distort in a rather drastic and distinct way. The DC lead preamp does NOT follow the Recto here, and since that is one of the Recto's most distinct circuit characteristics, this keeps the DC further from Recto land circuit-wise.
All said, it might be fair to say it borrows from both, and it's fair to say that, circuit-wise, the DC is unique enough in enough ways to be it's own thing, while remaining distinctly Boogie.
