I just purchased a 2nd hand DZ30 a week ago. The seller did a great packing job and the shippers apparently decided to put it to the test.It is housed in a beautiful hardwood cab with Matchless trannies and choke. As usual I removed the chassis and shook it upside down to see what came loose and then used a current limiter for the first turn on-all good. On a couple of ocassions it would hum horribly,I noticed the 2 left hand Power tube were redplating. I discovered a loose diode and connection on the Rectifier.Hey, shipped halfway across the US thats minor. I liked the sound better than my Rebel 30 but noticed a high bass or low mid tone that was annoying, maybe what friends would call a boxy sound.Really ugly on a neck humbucker-So I cleaned the pots and changed the Vol. brite caps to 100pf. Meh,slightly better but I figured the right speaker might be important, I have a 1x12 with a WGS -G12C/S that is barley broken in.Today I remembered I had a set of JJ el84s I bought 3 yrs. ago-in they went and WOW I am in amp heaven, it really suits my classic rock style.
         I was trying some OD pedals to see what works best and its the first time I have heard a Tube Screamer sound good (TS 9 and a TS 9DX). I do have some questions for Y"all

        1. I am concerned about the Rectifier diodes, they look a bit cooked.What do you recommend ?
        2. I noticed the wires to the effects jacks are sensitive to being moved during inspection,can they be replaced with shielded cable ? The loop sound fine with delay just wondering.
        3.Master vol. seems ok does a PPIMV make that much difference?
        4.Any speaker suggestions,I have multiple 1x12 and a couple 2x12 cabs but it seems the speakers I have may not be best suited.
      I will try to post a pics.