I bought a Mark IV head on ebay a while ago. I bought the combo cab to put the chassis in while I was using it. I really like sound of the Combo with the 3/4 back 1x12 cab under it.
I love the lead tones you can get out of the Mark IV, but when it was put up against my DC-10, the DC won because of the simplicity.
I never found a good use for R2, and figured that if I needed pedals to go along with my amp's huge footswitch, then I didn't need a 3 channel amp.
The DC-10 with an NOS tube in V4 (Clean channel) in my opinion, and for what I play, rose above the Mark. They were very close, the Mark had more chime, the DC had more thump. In the end, like I said, it was simplicity.
As for the DC-5,
I have a DC-10 & a DC-3. A good friend of mine wanted the DC-5, so I sold it to him. He's the guitar teacher at the local college and it went to the best home possible.
Right now, I have:
Blue Angel 1x12 combo - currently for sale, although it took much deliberation
DC-10 2x12 combo - all stock except for the tubes and bias pot
DC-3 1x12 combo - Cathode Biased, with a few minor mods
Heartbreaker head - Channel 1 is stock. Channel 2 has been modified to give a real JCM 800 tone. Reverb has been modded to be more present and thicker, although, this has the HB-2 board and the circuit was different than my last Heartbreaker, so it didn't need as much of a mod.
There is absolutely nothing wrong with the Mark IV, I just didn't like how tempramental it was. This was my 2nd one, and I tried all tube configurations, it simply wasn't the amp for me.
