Either channel set to modern will be loud. What it does is take out the negative feedback loop and in turn, the amp naturally gets super loud.
The modern mode on the DR does not have a real presence control. It is like an extra high treble knob. Due to the design of a non negative feedback circuit, this is totally normal. A negative feedback circuit basically takes some of the signal from you output tap and feeds it through the presence control to the phase inverter. Depending on the design, most amp makers use it to give a boost in the upper mids to add a bit more sizzle. To do this there is a small amount of resistance and capacitance involved, but the higher resistance the more output power and bottom end the amp will have.
A normal amount of NFB will make the amp sweeter and a bit lower in percieved output like the Vintage/Orange mode. This is just par for the circuit.
Soldano calls it the Depth Mod. I did this to my SLO 100 with a .05 cap across a 1 Meg pot before the 4 ohm tap. It is basically an adjustable negative feedback loop and when turned up it can really flap your pants like a DR in modern mode. Mesa just decided to use it flat out 0 NFB to make it brutal.
Lastly, your Volume pots are probably not identical. One set to 5 may be the othe one set to 3. The tapers are often unpredictable. You will probably have to tweak a bit to find the proper balance between the two channels. I know I had two and almost every DR I had. I have always ran my DR's through at least two cabinets. One cab is just not enough. With two cab you get the full effect of the amp and a better sense of how good they really sound. It has always seemed that one cab could not handle the sonic and power potential of the DR. The rig I amp playing with now is a 92 DR and a 1990 MK III. I split the signal with a TC Electronics SCF panned full left and full right with 0 intensity. It run the MK III through 1 4X12 and the DR through 2 4X12's in modern mode.
It has a slight hint of stereo separation and a large hint that I am ripping off Petrucci. HA !!!
Can anyone say Images and Words... Brutality and clarity with a crushing bottom end and sweet singing highs from the MK III.
